Dynamic voltage and frequency scaling in wireless modems

ABSTRACT

Methods and apparatuses are described in which dynamic voltage and frequency scaling may be used to save power when processing packets in a wireless communications device. In some cases, inframe detection may allow the device to determine whether to transition from a first (e.g., lower) voltage level to a second (e.g., higher) voltage level to process one or more packets of a received frame. For some packet types the first voltage level may be maintained. In other cases, the device may determine a bandwidth to use from among multiple bandwidths supported by the device. The bandwidth may be determined based on channel conditions. A voltage level may be identified that corresponds to the determined bandwidth and a processing voltage may be scaled to the identified voltage level. The device may be configured to operate in wireless local area network (WLAN) and/or in a cellular network (e.g., LTE).

CROSS-REFERENCES

The present application for patent claims priority to U.S. ProvisionalPatent Application No. 61/809,257, entitled “DYNAMIC VOLTAGE ANDFREQUENCY SCALING IN WIRELESS MODEMS” by Homchaudhuri et al., filed Apr.5, 2013, assigned to the assignee hereof, and expressly incorporated byreference herein.

BACKGROUND

Wireless communications networks are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, and the like. These wireless networks may be multiple-accessnetworks capable of supporting multiple users by sharing the availablenetwork resources.

A wireless communication network may include a number of network devicessuch as access points (APs) and/or base stations or Node-Bs that cansupport communication for a number of wireless devices. A wirelessdevice may communicate with a network device bidirectionally. Forexample, in cellular networks, a user equipment (UE) may communicatewith a base station via downlink and uplink. The downlink (or forwardlink) refers to the communication link from the base station to the UE,and the uplink (or reverse link) refers to the communication link fromthe UE to the base station. A similar form of communication may occurbetween a wireless device (e.g., station or STA) and an access point ina wireless local area network (WLAN).

In WLANs, for example, the access point may send data to at least oneclient device in the form of one or more frames. To reduce powerconsumption, a client device may operate in a low power consumption mode(e.g., a sleep mode) in some circumstances, such as when the clientdevice is not being used for communication with the access point. Inother circumstances, however, reducing the power consumption of theclient device may prove challenging because the bandwidth of the signalsreceived by the client device (e.g., signals carrying frames) may not beknown. In those cases, such as during a listening mode or an activereceive/transmit mode, for example, additional mechanisms may be neededto reduce power consumption. Moreover, similar mechanisms may also beneeded for wireless devices used in cellular networks (e.g., UEs).

SUMMARY

Methods and apparatuses are described for wireless communications inwhich dynamic voltage and frequency scaling (DVFS) may be used to savepower when processing packets in a wireless communications device. Insome cases, inframe or within frame detection may allow the wirelesscommunications device to determine whether to transition from a first(e.g., lower) voltage level to a second (e.g., higher) voltage level toprocess one or more packets of a received frame. The second voltage maybe selected from multiple voltages based, at least in part, on abandwidth. For example, different bandwidths may be used and eachbandwidth may have a different second voltage associated with it. Alower voltage level may be selected at first to enable sufficientprocessing (e.g., clocking frequency) of certain types of packets orframes. When a high or very high throughput packet is detected, applyinga higher voltage level may allow for higher clock frequencies that arethen used to digitally process the contents of the high or very highthroughput packets.

In some embodiments, the wireless communications device determines abandwidth to use from among multiple bandwidths supported by the device.For example, current WLAN devices may support 20 Megahertz (MHz), 40MHz, 80 MHz, and/or 160 MHz bandwidths. Other wireless devices maysupport more, fewer, and/or different bandwidths than a WLAN device. Thebandwidth may be determined based on channel conditions. Inopportunistic wireless systems the bandwidth may be determined usingClear Channel Assessment (CCA) techniques, or in another embodiment, thebandwidth is determined based on higher control plane decisions of thewireless protocol stack. A voltage level may be identified thatcorresponds to the determined bandwidth and a processing voltage may bescaled to the identified voltage level. For example, one bandwidth mayuse a first voltage level while a higher bandwidth may use a secondvoltage level higher than the first voltage level. As noted above, ahigher voltage level may allow for higher clock frequencies for digitalprocessing, which may be needed to sustain that mode of operation. Thewireless communications device may be configured to operate in a WLAN(also referred to as a Wi-Fi network) and/or in a cellular network(e.g., 3GPP Long Term Evolution or LTE).

A method for wireless communications includes operating at a firstvoltage level in a wireless communications device. The method includesdetecting, within a received frame, a frame metric associated with oneor more packets of the received frame. The method further includesdetermining whether to transition to a second voltage level to processat least a portion of the one or more packets of the received framebased on the detected frame metric. The frame metric may include one ormore of a throughput category, a destination of a packet, a transmissiongrant, and a reception grant. In some embodiments, the method includesapplying the second voltage level to one or more subsystems of thewireless communications device. Operating at different voltages mayresult in different clock frequencies for digital processing.

In some embodiments of the method, the method includes scaling from thefirst voltage level to the second voltage level, where the secondvoltage level is greater than the first voltage level. The method mayinclude scaling from the second voltage level to the first voltage levelfor a next received frame after processing the at least a portion of theone or more packets of the received frame at the second voltage level.The detecting may include detecting the frame metric within a preambleof the received frame.

In some embodiments of the method, the one or more packets in thereceived frame are IEEE 802.11ac packets. Each of the one or morepackets may be a very high throughput (VHT) packet, and the detectingmay include detecting the frame metric during the VHT short trainingfield (VHT-STF) of one or more the received VHT packets. The scalingfrom the first voltage level to the second voltage level may occurwithin the VHT packet, where the second voltage level is greater thanthe first voltage level. In some embodiments, the one or more packetsare high throughput (HT) packets, and the method includes scaling fromthe first voltage level to the second voltage level to process at leasta portion of one or more of the HT packets, where the second voltagelevel is greater than the first voltage level. In some embodiments, theone or more packets are legacy packets, and the method includesmaintaining the first voltage level for processing one or more of thelegacy packets.

In some embodiments of the method, the method includes determiningwhether the frame is destined for the wireless communications device,and operating at the first voltage level when the frame is not destinedfor the wireless communications device. The determining may includeidentifying a media access control (MAC) portion of the frame, anddetermining a destination of the frame from the MAC portion of theframe. The determining may include identifying a partial associationidentifier (pAID) field or a group identifier (GID) field in the frame,and determining a destination of the frame from the pAID field or theGID field.

In some embodiments of the method, the method includes identifying abandwidth associated with the one or more packets of received frame, andscaling from the first voltage level to the second voltage level basedat least in part on the frame metric and the identified bandwidth. Theframe metric may be a bandwidth associated with one or more packets ofthe received frame. The method may include identifying a differentbandwidth associated with the one or more packets of received frame, andscaling from the second voltage level to a third voltage level based atleast in part on the frame metric and the identified differentbandwidth. In some embodiments, the method may include scaling from afirst clock frequency (e.g., a first clock frequency for digitalprocessing) to a second clock frequency (e.g., a second clock frequencyfor digital processing) based on the frame metric, where the secondclock frequency is greater than the first clock frequency.

In some embodiments of the method, the frame includes an LTE sub-framehaving a first slot and a second slot, where the first slot includes aregion with physical downlink control channel (PDCCH) information, andthe detecting includes detecting the frame metric within the region inthe first slot. In some embodiments, the method includes determiningfrom the frame metric whether a portion of the frame is to be decoded byan LTE modem and scaling from the first voltage to the second voltage toprocess the portion of the frame when a determination is made that theportion of the frame is not to be decoded by the LTE modem.

A method for wireless communications includes determining a bandwidth tobe used at a wireless communications device from multiple bandwidthssupported by the wireless communications device (e.g., 20 MHz, 40 MHz,80 MHz, and/or 160 MHz for WLAN devices). The method includesidentifying a voltage level to use at the wireless communications devicebased on the determined bandwidth. The method also includes scaling avoltage level to the identified voltage level to process a frame. Insome embodiments, the method includes transmitting the frame whileoperating at the scaled voltage level. In some embodiments, the methodincludes receiving the frame having one or more packets, and processingat least a portion of the one or more packets of the received frame atthe scaled voltage level. In some embodiments, the method includesreceiving the frame having one or more packets, detecting, within thereceived frame, a frame metric associated with one or more packets ofthe received frame, and processing at least a portion of the one or morepackets of the received frame at the scaled voltage level based on theframe metric and the determined bandwidth.

In some embodiments of the method, each of the bandwidths supported bythe wireless communications device has a corresponding voltage levelthat is different from the voltage level of another bandwidth, and theidentified voltage level is the voltage level corresponding to thedetermined bandwidth. In some embodiments, the method includesadjusting, based on the determined bandwidth, one or more physical layer(PHY) clocks or similar sources of timing or synchronization signalsthat are used by the wireless communications device.

In some embodiments of the method, the determining includes determiningthe bandwidth to be used at the wireless communications device based onchannel conditions (e.g., CCA techniques) associated with the wirelesscommunications device. The scaling may include scaling to the identifiedvoltage level from a voltage level corresponding to a bandwidthdifferent from the determined bandwidth. The method may include applyingthe scaled voltage level to one or more subsystems of the wirelesscommunications device.

An apparatus for wireless communications includes means for operating ata first voltage level in a wireless communications device. The apparatusincludes means for detecting, within a received frame, a frame metricassociated with one or more packets of the received frame. The apparatusalso includes means for determining whether to transition to a secondvoltage level to process at least a portion of the one or more packetsof the received frame based on the detected frame metric.

An apparatus for wireless communications includes means for determininga bandwidth to be used at a wireless communications device from multiplebandwidths supported by the wireless communications device. Theapparatus includes means for identifying a voltage level to use at thewireless communications device based on the determined bandwidth. Theapparatus also includes means for scaling a voltage level to theidentified voltage level to process a frame.

A wireless communications device includes a processor and a memory inelectronic communication with the processor, where instructions storedin the memory are executable by the processor to operate at a firstvoltage level in the wireless communications device, to detect, within areceived frame, a frame metric associated with one or more packets ofthe received frame, and to determine whether to transition to a secondvoltage level to process at least a portion of the one or more packetsof the received frame based on the detected frame metric.

A wireless communications device includes a processor and a memory inelectronic communication with the processor, where instructions storedin the memory are executable by the processor to determine a bandwidthto be used at the wireless communications device from multiplebandwidths supported by the wireless communications device, to identifya voltage level to use at the wireless communications device based onthe determined bandwidth, and to scale a voltage level to the identifiedvoltage level to process a frame.

A wireless communications device includes a detector configured todetect, within a received frame, a frame metric associated with one ormore packets of the received frame. The device includes a voltageadjuster configured to operate at a first voltage level, and todetermine whether to transition to a second voltage level to process atleast a portion of the one or more packets of the received frame basedon the detected frame metric.

A wireless communications device includes a bandwidth identifierconfigured to determine a bandwidth to be used at the wirelesscommunications device from multiple bandwidths supported by the wirelesscommunications device. The device includes a voltage adjuster configuredto identify a voltage level to use at the wireless communications devicebased on the determined bandwidth, and to scale a voltage level to theidentified voltage level to process a frame.

A computer program product includes a non-transitory computer-readablemedium having code for causing at least one computer to operate at afirst voltage level in a wireless communications device. Thenon-transitory computer-readable medium includes code for causing the atleast one computer to detect, within a received frame, a frame metricassociated with one or more packets of the received frame. Thenon-transitory computer-readable medium also includes code for causingthe at least one computer to determine whether to transition to a secondvoltage level to process at least a portion of the one or more packetsof the received frame based on the detected frame metric.

A computer program product includes a non-transitory computer-readablemedium having code for causing at least one computer to determine abandwidth to be used at a wireless communications device from multiplebandwidths supported by the wireless communications device. Thenon-transitory computer-readable medium includes code for causing the atleast one computer to identify a voltage level to use at the wirelesscommunications device based on the determined bandwidth. Thenon-transitory computer-readable medium also includes code for causingthe at least one computer to scale a voltage level to the identifiedvoltage level to process a frame.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the spirit and scope of the appended claims. Features whichare believed to be characteristic of the concepts disclosed herein, bothas to their organization and method of operation, together withassociated advantages will be better understood from the followingdescription when considered in connection with the accompanying figures.Each of the figures is provided for the purpose of illustration anddescription only, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentdisclosure may be realized by reference to the following drawings. Inthe appended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 shows a diagram that illustrates an example of a wirelesscommunications system according to various embodiments;

FIG. 2 shows a diagram that illustrates an example of a wireless localarea network (WLAN) system according to various embodiments;

FIG. 3 shows a block diagram that illustrates an example of a wirelessmodem architecture according to various embodiments;

FIG. 4A shows a diagram that illustrates an example of inframe detectionfor dynamic voltage and frequency scaling according to variousembodiments;

FIG. 4B shows a diagram that illustrates another example of inframedetection for dynamic voltage and frequency scaling according to variousembodiments;

FIG. 4C shows a diagram that illustrates an example of bandwidth-baseddynamic voltage and frequency scaling according to various embodiments;

FIG. 4D shows a diagram that illustrates an example of packetdestination information in dynamic voltage and frequency scalingaccording to various embodiments;

FIG. 4E shows a diagram that illustrates another example of packetdestination information in dynamic voltage and frequency scalingaccording to various embodiments;

FIG. 5 shows a diagram that illustrates an example of inframe detectionin an IEEE 802.11ac very high throughput (VHT) packet according tovarious embodiments;

FIG. 6 shows a diagram that illustrates an example of inframe detectionfor various IEEE 802.11x packets according to various embodiments;

FIG. 7 shows a diagram that illustrates examples of a timeline of packetprocessing for errors according to various embodiments;

FIG. 8A shows a block diagram that illustrates an example of anarchitecture for dynamic voltage and frequency scaling of modemsubsystems according to various embodiments;

FIG. 8B shows a block diagram that illustrates an example of anarchitecture for dynamic voltage and frequency scaling of radiofrequency (RF) modem subsystems according to various embodiments;

FIG. 9A shows a block diagram that illustrates an example of directvoltage scaling according to various embodiments;

FIG. 9B shows a block diagram that illustrates an example of indirectvoltage scaling according to various embodiments;

FIG. 10 shows a block diagram that illustrates an example of an LTEframe structure for use in dynamic voltage and frequency scalingaccording to various embodiments;

FIG. 11A shows a diagram that illustrates an example of long and shortdiscontinuous reception (DRX) intervals in LTE according to variousembodiments;

FIG. 11B shows a diagram that illustrates an example of dynamic voltageand frequency scaling during DRX intervals according to variousembodiments;

FIG. 11C shows a diagram that illustrates an example of dynamic voltageand frequency scaling during measurement gaps according to variousembodiments;

FIG. 12 shows a block diagram that illustrates an example of a wirelesscommunications device architecture according to various embodiments;

FIG. 13 shows a block diagram that illustrates an example of a networkdevice architecture according to various embodiments;

FIG. 14A shows a block diagram that illustrates an example of a dynamicscaling and frequency module according to various embodiments;

FIG. 14B shows a block diagram that illustrates another example of adynamic scaling and frequency module according to various embodiments;

FIG. 15 shows a block diagram that illustrates an example of amultiple-input multiple-output (MIMO) communications system according tovarious embodiments;

FIG. 16 is a flowchart of an example of a method for dynamic voltage andfrequency scaling according to various embodiments;

FIG. 17 is a flowchart of an example of another method for dynamicvoltage and frequency scaling according to various embodiments;

FIG. 18 is a flowchart of an example of yet another method for dynamicvoltage and frequency scaling according to various embodiments;

FIG. 19 is a flowchart of an example of a method for dynamic voltage andfrequency scaling according to various embodiments;

FIG. 20 is a flowchart of an example of another method for dynamicvoltage and frequency scaling according to various embodiments; and

FIG. 21 is a flowchart of an example of yet another method for dynamicvoltage and frequency scaling according to various embodiments.

DETAILED DESCRIPTION

Described embodiments are directed to methods and apparatuses forwireless communications in which dynamic voltage and frequency scaling(DVFS) may be used to save power when processing packets in a wirelesscommunications device. In some cases, inframe detection may allow thedevice (e.g., UE, STA) to determine whether to transition from a first(e.g., lower) voltage level to a second (e.g., higher) voltage level toprocess one or more packets of a received frame. A lower voltage levelmay be selected at first to enable sufficient processing (e.g., clockingfrequency) of certain types of packets or frames. When a high or veryhigh throughput packet is detected, applying a higher voltage level mayallow for higher clock frequencies that are then used to digitallyprocess the contents of the high or very high throughput packets.

In some embodiments, the wireless communications device may determine abandwidth to use from among multiple bandwidths supported by the device.WLAN devices, for example, may support 20 MHz, 40 MHz, 80 MHz, and/or160 MHz bandwidths. The bandwidth may be determined based on channelconditions. A voltage level may be identified that corresponds to thedetermined bandwidth and a processing voltage may be scaled to theidentified voltage level. For example, one bandwidth may use a firstvoltage level while a higher bandwidth may use a second voltage levelhigher than the first voltage level. As noted above, a higher voltagelevel may allow for higher clock frequencies for digital processing.While an increase in digital clock frequency to handle higher bandwidthsis typically associated with an increase in the voltage level, there maybe some instances in which the voltage is already higher than requiredfor a particular digital clock frequency leaving room for scaling thedigital clock frequency slightly higher.

The wireless communications device may be configured to operate in anywireless network such as, but not limited to a wireless local areanetwork (WLAN) and/or in a cellular network (e.g., LTE). WLAN may referto a network that is based on the protocols described in the variousIEEE 802.11 standards (e.g., IEEE 802.11a/g, IEEE 802.11n, IEEE802.11ac, IEEE 802.11ah, etc.), including draft standards orsubsequently developed wireless local area networking standards. Whenthe device is operated in a cellular network, the voltage scaling (andcorresponding digital clock frequency scaling) may be determined basedon uplink (UL) and downlink (DL) scheduling conditions. For example, aninframe or within frame detection scheme may be used to determinewhether the wireless communications device is scheduled to receive ortransmit information to a base station. In some cases, the operatingvoltage level may be reduced until a scheduled reception or transmissionis scheduled to take place.

Techniques described herein may be used for various wirelesscommunications systems such as cellular wireless systems, Peer-to-Peerwireless communications, WLANs, ad hoc networks, satellitecommunications systems, and other systems. The terms “system” and“network” are often used interchangeably. These wireless communicationssystems may employ a variety of radio communication technologies such asCode Division Multiple Access (CDMA), Time Division Multiple Access(TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA(OFDMA), Single-Carrier FDMA (SC-FDMA), and/or other radio technologies.Generally, wireless communications are conducted according to astandardized implementation of one or more radio communicationtechnologies called a Radio Access Technology (RAT). A wirelesscommunications system or network that implements a Radio AccessTechnology may be called a Radio Access Network (RAN).

Examples of Radio Access Technologies employing CDMA techniques includeCDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases 0 and Aare commonly referred to as CDMA2000 1×, 1×, etc. IS-856 (TIA-856) iscommonly referred to as CDMA2000 1×EV-DO, High Rate Packet Data (HRPD),etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA.Examples of TDMA systems include various implementations of GlobalSystem for Mobile Communications (GSM). Examples of Radio AccessTechnologies employing OFDM and/or OFDMA include Ultra Mobile Broadband(UMB), Evolved UTRA (E-UTRA), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of UniversalMobile Telecommunication System (UMTS). LTE and LTE-Advanced (LTE-A) arenew releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A,and GSM are described in documents from an organization named 3GPP or“3rd Generation Partnership Project.” CDMA2000 and UMB are described indocuments from an organization named “3rd Generation Partnership Project2” (3GPP2). The techniques described herein may be used for the systemsand radio technologies mentioned above as well as other systems andradio technologies.

Thus, the following description provides examples, and is not limitingof the scope, applicability, or configuration set forth in the claims.Changes may be made in the function and arrangement of elementsdiscussed without departing from the spirit and scope of the disclosure.Various embodiments may omit, substitute, or add various procedures orcomponents as appropriate. For instance, the methods described may beperformed in an order different from that described, and various stepsmay be added, omitted, or combined. Also, features described withrespect to certain embodiments may be combined in other embodiments.

FIG. 1 shows a wireless network 100 for communication, which may includean LTE/LTE-A network and a wireless network such as a WLAN. It should benoted that while the example illustrates use of an LTE-A network andWLAN, any various wireless networks may be used, as previouslymentioned. The wireless network 100 includes a number of evolved node Bs(eNBs) 105 and other network entities or devices. An eNB may be astation that communicates with the UEs and may also be referred to as abase station, a node B, an access point, or the like. Each eNB 105 mayprovide communication coverage for a particular geographic area. In3GPP, the term “cell” can refer to a particular geographic coverage areaof an eNB and/or an eNB subsystem serving the coverage area, dependingon the context in which the term is used.

An eNB may provide communication coverage for a macro cell, a pico cell,a femto cell, and/or other types of cells. A macro cell generally coversa relatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscriptions withthe network provider. A pico cell would generally cover a relativelysmaller geographic area and may allow unrestricted access by UEs withservice subscriptions with the network provider. A femto cell would alsogenerally cover a relatively small geographic area (e.g., a home) and,in addition to unrestricted access, may also provide restricted accessby UEs having an association with the femto cell (e.g., UEs in a closedsubscriber group (CSG), UEs for users in the home, and the like). An eNBfor a macro cell may be referred to as a macro eNB. An eNB for a picocell may be referred to as a pico eNB. And, an eNB for a femto cell maybe referred to as a femto eNB or a home eNB. In the example shown inFIG. 1, the eNBs 105-a, 105-b, and 105-c are macro eNBs for the macrocells 110-a, 110-b, and 110-c, respectively. The eNB 105-x is a pico eNBfor the pico cell 110-x. A femto eNB is not shown but may be included inthe wireless network 100. An eNB may support one or multiple (e.g., two,three, four, and the like) cells. Together the eNBs 105-a, 105-b, 105-c,pico eNB 105-x, and femto eNB (not shown) may be referred to as eNBs (oreNBs 105) in this disclosure.

The wireless network 100 may support synchronous or asynchronousoperation. For synchronous operation, the eNBs may have similar frametiming, and transmissions from different eNBs may be approximatelyaligned in time. For asynchronous operation, the eNBs may have differentframe timing, and transmissions from different eNBs may not be alignedin time. The techniques described herein may be used for eithersynchronous or asynchronous operations.

A network controller 130 may couple to a set of eNBs and providecoordination and control for these eNBs. The network controller 130 maycommunicate with the eNBs 105 via a backhaul 132. The eNBs 105 may alsocommunicate with one another, e.g., directly or indirectly via awireline backhaul 134 or a wireless backhaul 136.

The UEs 115 are dispersed throughout the wireless network 100, and eachUE may be stationary or mobile. A UE 115 may also be referred to bythose skilled in the art as a mobile station, a subscriber station, amobile unit, a subscriber unit, a wireless unit, a remote unit, a mobiledevice, a wireless device, a wireless communications device, a remotedevice, a mobile subscriber station, an access terminal, a mobileterminal, a wireless terminal, a remote terminal, a handset, a useragent, a mobile client, a client, or some other suitable terminology. AUE 115 may be a cellular phone, a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, atablet computer, a laptop computer, a cordless phone, a wireless localloop (WLL) station, or the like. A UE may be able to communicate withmacro eNBs, pico eNBs, femto eNBs, relays, and the like.

The wireless network 100 shows transmissions 125 between mobile devices115 and base stations 105. The transmissions 125 may include uplink (UL)and/or reverse link transmission, from a mobile device 115 to a basestation 105, and/or downlink (DL) and/or forward link transmissions,from a base station 105 to a mobile device 115. LTE/LTE-A utilizes OFDMAon the downlink and SC-FDMA on the uplink. OFDMA and SC-FDMA partitionthe system bandwidth into multiple (K) orthogonal subcarriers, which arealso commonly referred to as tones, bins, or the like. Each subcarriermay be modulated with data. The spacing between adjacent subcarriers maybe fixed, and the total number of subcarriers (K) may be dependent onthe system bandwidth. The system bandwidths may be 1.25, 2.5, 5, 10 or20 MHz, for example. For these bandwidths, corresponding Fast FourierTransforms (FFTs) of 128, 256, 512, 1024 or 2048 points may be used toprocess data. The system bandwidth may also be partitioned intosub-bands. For example, a sub-band may cover 1.08 MHz, and there may be1, 2, 4, 8 or 16 sub-bands for a corresponding system bandwidth of 1.25,2.5, 5, 10 or 20 MHz, respectively.

Also shown in FIG. 1 are two access points (APs) 120, where the first isconnected to a UE 115 (e.g., STA) in cell 110-a and the second isconnected to another UE 115 (e.g., STA) in cell 110-c. The UEs maycommunicate with the access points through transmissions 126. In thisexample, the UEs connected to the APs 120 may be dual mode devices thatsupport communication with both a cellular network and WLAN. Each of theAPs 120 has a coverage area 122 and may support one or more protocolsdescribed in the various IEEE 802.11 standards.

FIG. 2 shows a diagram 200 that includes an example of a WLAN, such asthe WLANs described above with reference to FIG. 1. An access point120-a in FIG. 2, which may be an example of the access points 120 ofFIG. 1, may generate a wireless local area network, such as an IEEE802.11 network, or so-called Wi-Fi network, with wireless client devices115-a. The WLAN may be associated with a coverage area 122-a. The clientdevices 115-a may be examples of the UEs 115 connected to the APs 120 inFIG. 1.

The access point 120-a may use a wired or wireless communicationsprotocol to establish a communications link with a data or contentnetwork (not shown), and/or with a wide area network (not shown). Forexample, the access point 120-a may use one or more of a cable modem, adigital service link (DSL) modem, an optical communications link such asa T1 or T3 line, or any other form of wired communications protocol tocommunicatively couple with another network. In another example, theaccess point 120-a may be wirelessly coupled to a data or contentnetwork and/or to a wide area network. For example, the access point120-a may be wirelessly coupled to a cellular network (e.g., 3G, 4G)such as the one described above with reference to FIG. 1. The accesspoint 120-a may include a wired (e.g., Ethernet) or wireless (e.g.,Wi-Fi) router, or a cellular to Wi-Fi hotspot device to allow one ormore of the client devices 115-a to communicate with another network.

The wireless devices used in both the wireless network 100 of FIG. 1 andthe WLAN of FIG. 2 may include a modem or other like device that mayenable dynamic voltage and frequency scaling (DVFS) to save power whenprocessing packets or frames. DVFS enables the adjustment or scaling ofdigital clock frequencies at each packet or frame to provide asufficient clock frequency to digitally process the contents of thatpacket or frame at specific bandwidths. The scaling of digital clockfrequencies is typically accompanied by a corresponding voltage scalingto provide the appropriate power to produce the digital clock frequency.For example, to handle data processing at higher bandwidths, a voltagemay be increased (higher power) to produce a higher digital clockfrequency. On the other hand, to handle data processing at lowerbandwidths, a lower voltage (lower power) may be sufficient to producean appropriate digital clock frequency. Therefore, in DVFS, a referenceto voltage scaling may also be a reference to the corresponding scalingof digital clock frequencies. The descriptions provided below detailvarious aspects of the techniques that may be used enable power savingsin a wireless device by using DVFS.

FIG. 3 shows a device 300 that may be part of a wireless modem. Thedevice 300 may in some cases be implemented in conjunction with one ofthe UEs 115, eNBs 105, or APs 120 described with reference to FIG. 1 orFIG. 2. The device 300 may be used for WLAN or cellular communications.The device 300 may also be a processor. The device 300 may include acentral processing unit (CPU) module 310, an interface module 315, a MAClayer module 320 (or simply MAC module 320), a PHY layer module (orsimply PHY module 330), a power management module 360, and a memory(MEM) module 370. The PHY module 330 may include a baseband module 340and a transceiver module 350. Each of these components may be incommunication with each other.

The components of the device 300 may, individually or collectively, beimplemented with one or more application-specific integrated circuits(ASICs) adapted to perform some or all of the applicable functions inhardware. Alternatively, the functions may be performed by one or moreother processing units (or cores), on one or more integrated circuits.In other embodiments, other types of integrated circuits may be used(e.g., Structured/Platform ASICs, Field Programmable Gate Arrays(FPGAs), and other Semi-Custom ICs), which may be programmed in anymanner known in the art. The functions of each unit may also beimplemented, in whole or in part, with instructions embodied in amemory, formatted to be executed by one or more general orapplication-specific processors.

The CPU module 310 may be configured to provide higher level processingof data and/or control information. The CPU module 310 may, in somecases, include one or more processors, microcontrollers, and/or likedevices, some of which may be based on an advance microcontroller busarchitecture (AMBA), for example.

The interface module 315 may be configured to include a peripheralcomponent interconnect express (PCIE)/universal serial bus (USB)/securedigital input output (SDIO) bridge for the data pipe between the CPUmodule 310 and the MAC module 320.

The MAC module 320 may be configured to provide an interface between adata link layer (layer 2 in the Open Systems Interconnection (OSI)model) and the network's physical layer (e.g., PHY module 330). The MACmodule 320 may, in some cases, be referred to as a media accesscontroller.

The PHY module 330 may be configured to provide an interface between theMAC module 320 and the physical medium (not shown). In WLANs, forexample, the PHY module 330 operations may include radio frequency (RF)operations, mixed-signal and analog portions of PHY layer processing,and digital baseband (BB) processing. The digital baseband processingmay be handled by, for example, a digital signal processor (DSP) in thebaseband module 340. The RF operations and mixed-signal and analogportions of PHY layer processing may be part of the transceiver module350. The transceiver module 350 may be configured to wirelessly transmitand/or receive frames or packets.

The power management module 360 may be configured to control or adjustthe power (e.g., voltage, clock frequency) used in one or more of thecomponents of the device 300. For example, the power management module360 may adjust the Vdd used by the device 300. Vdd refers to the powersupply voltage used in integrated circuit architectures. Other terms maybe used to refer to the power supply voltage. Adjusting the power supplyvoltage of a component of the device 300 may result in an correspondingadjustment of the digital clock frequency used by that component. Thepower management module 360 may be configured to implement some or allof the techniques described herein for dynamic voltage and frequencyscaling. In some cases, the power management module 360 may be part of apower management unit (PMU) and/or a power management integrated circuit(PMIC), for example.

The memory module 370 may be configured to store data associated withvarious aspects of the operation of the device 300, includinginitiation/configuration data, intermediate/processing data, software,firmware, and the like.

When the device 300 is used as part of a WLAN modem (e.g., UE 115, AP120), for example, the device 300 may support different modes ofoperation. One mode may correspond to a channel bandwidth of 20 MHz.This mode may be used with legacy WLAN packets (e.g., IEEE 802.11a/g)and may be referred to as HT20 (referring to high throughput 20 MHz).Another mode may correspond to a higher channel bandwidth, typically 40MHz. This mode may be used with high throughput (HT) WLAN packets (e.g.,IEEE 802.11n) and may be referred to as HT40. In some cases, the WLANmay support a mode with a channel bandwidth of 80 MHz. This mode may beused with very high throughput (VHT) WLAN packets (e.g., IEEE 802.11ac)and may be referred to as VHT80. The device 300 may also support staticand dynamic modes of operation.

In a static HT20 mode for search and receive operations, it may bepossible for a clock used with the PHY (e.g., PHY module 330) to operateat the lowest allowable frequency (and corresponding voltage) for anentire frame receive (frame-RX) operation. A nominal Vdd (e.g., 1.1V,tailored to the specific fabrication process node) may be typicallyapplied to the digital modem (e.g., BB/MAC) and RF blocks. This approachmay be used in connection with early reception (Early-Rx), beaconreception (Beacon-Rx), listen (search mode), and data receive (Data-Rx),for example.

In a dynamic HT20/HT40/VHT80 listen mode, it may be possible to operateat a scaled PHY clock (and scaled PHY voltage) during a frame listenzone (e.g., up to a VHT short training field (VHT-STF) in a preamble ofa packet or frame) (see e.g., FIG. 4A and FIG. 4B) before deciding to(1) abort the frame reception (Frame-Rx) because of errors or becausethe frame is not destined for the device, or (2) scale up (i.e.,increase) the PHY clock (and PHY voltage) to receive at a higherbandwidth. Typically, however, a nominal Vdd (1.1V) is applied duringthe entire packet or frame reception, leading to higher powerconsumption in the listen mode. Any power savings that may be achievedduring listen mode may significantly reduce power consumption insemi-active loads.

In a dynamic HT20/HT40/VHT80 transmit and receive (Tx/Rx) mode, the MAC(e.g., MAC module 320) may use a just-in-time bandwidth detection usingclear channel assessment (CCA) techniques to decide whether to transmita packet at 20/40/80 MHz (in some cases 160 MHz may also be supported).If a packet is relegated to a lower bandwidth transmission, the PHY(e.g., PHY module 330) may operate with a scaled back clock during thepacket transmission. When higher bandwidth transmissions are possible(from CCA operations), the PHY may transmit using higher clocks. Inthese examples, the entire packet or frame may be transmitted using theappropriate clock (voltage). In the receive mode, depending on abandwidth (BW) indication in the HT-SIG or VHT-SIG field of thepreamble, the PHY may operate at a lower clock (and reduced voltage)when an HT40 packet is received instead of a VHT80 or VHT160 packet. Theclock (voltage adjustment may take place inframe and a portion of thepacket or frame is processed at the appropriate clock (voltage).Typically, however, a nominal Vdd (1.1V) is used in both transmit andreceive modes.

For an LTE modem (e.g., UE 115, eNB 105, device 300), the downlinkscheduling control information (DCI) messages in a physical downlinkcontrol channel (PDCCH) may need to be decoded every 1 millisecond (ms).The scheduling information may indicate that a downlink (DL) or uplink(UL) grant may or may not have been provided to the UE by the eNodeB.When a DL grant is not provided, it may be sub-optimal to clock the LTEmodem at highest clock or at nominal Vdd for the remainder of thesub-frame. Furthermore, when a UL grant is provided, it may still besub-optimal to process the remainder of the sub-frame at the highestclock and voltage since the UE needs to act 4 ms later. A similar issuemay arise with respect to the long and short discontinuous reception(DRX) intervals and measurement gaps used in LTE.

Additional details on how to implement dynamic voltage and frequencyscaling in a WLAN modem or in an LTE modem are described below withrespect to various embodiments.

With respect to a static HT20 mode for listen and receive, for example,it may be possible to operate at a reduced Vdd (e.g., 0.9V or lower)during the entire listen and frame-RX phase once the WLAN modem isconfigured in the static HT20 mode. This reduced Vdd is lower than thenominal Vdd (1.1V) described above. The configuration of the WLAN modeminto this particular mode may be based on knowledge of the channelbandwidth being used in the reception of packets or frames. That is, theWLAN modem may receive an indication of the channel (connection)bandwidth and may switch to the static HT20 mode with its lower Vdd (andlower clock).

With respect to the dynamic HT40/VHT80 mode for listen, for example, itmay be possible to operate at a reduced Vdd (e.g., 0.9V or lower) duringthe entire listen phase. When a VHT packet is detected, the voltage maybe scaled from the reduced Vdd up to a nominal Vdd over a certain periodof time. In one example, a slew rate of ˜0.2V/3 microseconds (μs) may beprovided by a PMIC (e.g., power management module 360). Other slew ratesmay be used, some of which may be faster that 0.2V/3 μs. To provide theappropriate voltage level, switched-mode power supplies (SMPS) orlow-dropout linear regulators (LDOs) may be used with level shiftersacross different voltage domains (e.g., voltage islands) of the modemarchitecture.

In addition to the voltage adjustment (and corresponding clock frequencyadjustment) based on the throughput and/or bandwidth of a particularpacket, there may be other aspects that determine whether to adjust thevoltage, power, and/or frequency of operations in a wireless modem.

For example, for VHT packets (e.g., VHT80 packets), certain fields ofthe packet may be used to determine if the packet is destined for thewireless device (e.g., STA). For single user multiple-inputmultiple-output (MIMO) systems, the field inspected for the destinationinformation may be partial association identifier (pAID), while fordownlink (DL) multi-user MIMO (MU-MIMO), the field inspected for thedestination information may be group identifier (GID). When the packetis destined for the STA, the WLAN modem may remain enabled at a highsupply voltage and frequency, subject to decisions based on dynamicbandwidth indicated in the preamble fields. When the packet is notdestined for the STA, the WLAN modem may select one of several options:(1) clock gate itself (e.g., MAC/BB) and the RF portions; (2) performthe same operations as in (1) and also scale Vdd down (e.g., 0.9V) forthe duration of the packet or data unit (e.g., Physical LayerConvergence Protocol (PLCP) Protocol Data Unit or PPDU); and (3) performthe same operations as in (1) and power gate the entire MAC/BB/RFdomains (e.g., MAC module 320, baseband module 340, and transceivermodule 350). The selection of one of these options may depend on thelength of the PPDU, and/or on the associated slew rate of a PMIC (e.g.,power management module 360) and power collapse/restore latencies of thePMIC. That is, the selection depends on how long the packets are and howlong does it take to make a voltage/frequency transition.

For high throughput (e.g., HT40) and legacy (e.g., HT20) packets, thedetection of the destination of the packet may occur within the MACheader in the packet. The voltage and frequency of the WLAN modem (e.g.,device 300) may remains at the higher or maximum level for the durationof the HT-STF until the MAC receiver address (RA) is found. When thepacket is not destined for the STA, it may be possible to apply one ofthe techniques (1), (2), and (3) described above with respect to the VHTpackets. When the packet is directed or destined for the STA, thenominal voltage or the reduced voltage, commensurate with the incomingbandwidth mode, and the corresponding frequency, may be maintained untilthe completion of frame-RX.

Other events that may cause dynamic voltage and frequency scaling in awireless modem may include a failure in a cyclic redundancy check (CRC)delimiter or termination of frame-RX from continuous PHY metrics. Forexample, the clock and the voltage may be scaled for the remainder of aframe that has encountered a delimiter CRC failure in an aggregated MACprotocol data unit (A-MPDU). In another example, clock scaling andvoltage scaling may be applied as a trigger from the continuous PHYmetric decisions, such as predicting in the middle of the Frame-Rx thatthe eventual Frame Check Sequence is likely to fail the integrity checkand aborting the Frame-Rx mid-frame.

In dynamic HT40/VHT80 transmit and receive (Tx/Rx) mode, for thosepackets that are directed or destined for the STA it may be possible tofirst decode the bandwidth (BW) field from a (V)HT-SIG-A field. Using atable or some other like device (e.g., a BW-to-Frequency lookup table orLUT), the PHY clocks may be adjusted or chose appropriately (e.g.,frequency for 20 MHz (f_20), frequency for 40 MHz (f_40), frequency for80 MHz (f_80), frequency for 160 MHz (f_160)) and Vdd scaled fromnominal Vdd (e.g., Vdd 160=1.1V) down to Vdd for 20 MHz or Vdd 20 (e.g.,0.9V or below) in finer steps. This approach allows for DVFS to be usedin active RX as well as during active TX (based on CCA and/or dynamic BWdecisions).

The various modes described herein have been provided by way ofillustration and not of limitation. A wireless modem or other similar orlike device may use more, fewer, and/or different modes withoutdeparting from the various aspects presented in the disclosure relatedto dynamic voltage and frequency scaling.

The descriptions of FIGS. 4A-6 presented below provide some examples ofthe techniques for dynamic voltage and frequency scaling describedabove. Turning next to FIG. 4A, a diagram 400 is shown that includes aframe or packet 410 with a first portion 420 representing a preamble orheader of the frame 410, and a second portion 430 representing the datacontents of the frame 410. The frame or packet 410 need not be limitedto a WLAN frame or packet and may instead correspond to a frame orpacket in any of multiple wireless communications protocols. FIG. 4Adescribes a mechanism by which a wireless modem (e.g., UE 115, AP 120,eNB 105, device 300) may first operate at a first voltage level 440(V0), may then detect within the frame 410 a frame metric (e.g.,throughput category, packet destination, transmission grant, receptiongrant) associated with one or more packets of the frame 410, and maythen determine whether to transition to a second voltage level 445 (V1)to process at least a portion of the one or more contiguous packets ofthe frame 410 based on the detected frame metric. The first voltagelevel 440 may correspond to one digital clock frequency and the secondvoltage level 445 may correspond to a higher digital clock frequency.

In this example, the detection of a throughput category may occur withinthe first portion 420 of the frame 410 and during a period 450. At theend of the period 450, the determination of whether the frame 410 has athroughput that involves a higher voltage level is made. When thecurrent voltage level (V0) (and corresponding digital clock frequency)is appropriate or sufficient to process the frame 410, no change is madeand the current voltage level is maintained. When the current voltagelevel is not sufficient and the second voltage level (V1) (andcorresponding digital clock frequency) is needed to process the dataportion of the frame 410, a voltage transition (i.e., scaling) occursduring a period 455 until the appropriate voltage level (V1) is reached.A period 460 corresponds to the application of the higher voltage levelfor digital processing of the remaining portion of the frame 410.

Turning to FIG. 4B, a diagram 400-a is shown that includes the frame orpacket 410 of FIG. 4A. FIG. 4B describes a mechanism by which a wirelessmodem (e.g., UE 115, AP 120, eNB 105, device 300) may first operate at afirst voltage level 440 (V0), may then detect within the frame 410 aframe metric associated with one or more packets of the frame 410, andmay then determine whether to transition to a next voltage level (e.g.,445 (V1), 446 (V2), 447 (Vn)) to process at least a portion of the oneor more packets of the frame 410 based on the detected frame metric. Thefirst voltage level 440 may correspond to one digital clock frequencyand the other voltage levels may correspond to higher digital clockfrequencies.

As with the example of FIG. 4A, the detection of a throughput categorymay occur within the first portion 420 of the frame 410 and during aperiod 450. At the end of the period 450, the determination of whetherthe frame 410 has a throughput that involves a higher voltage level ismade. In this example, however, there may be multiple levels of higherthroughput (e.g., HT40/VHT80/VHT160) and the determination may includewhich of these throughputs is associated with the frame 410. Once thethroughput is determined, the proper voltage level (and correspondingdigital clock frequency) may also need to be identified. When thecurrent voltage level (V0) is appropriate or sufficient to process theframe 410, no change is made and the current voltage level ismaintained. When the current voltage level is not sufficient to handlethe throughput of frame 410 and a higher voltage level (and higherdigital clock frequency) is needed, a voltage transition (i.e., scaling)occurs during the period 455 until the voltage level identified tocorrespond to the throughput level of frame 410 is reached. The period460 again corresponds to the application of the higher voltage level fordigital processing of the remaining portion of the frame 410.

Turning next to FIG. 4C, a diagram 400-b is shown that includes theframe or packet 410 of FIG. 4A and FIG. 4B. FIG. 4C describes amechanism by which a bandwidth (BW) to be used at a wirelesscommunications device (e.g., UE 115, AP 120, eNB 105, device 300) isdetermined from multiple bandwidths supported by the device. For WLANmodems (radios), for example, bandwidths supported may include 20 MHz,40 MHz, 80 MHz, and/or 160 MHz. Other modems may support more, fewer,and/or different bandwidths. A voltage level to use at the wirelesscommunications device may be identified based on the determinedbandwidth and a voltage level (and corresponding digital clockfrequency) may be scaled to the identified voltage level.

In this example, the bandwidth and corresponding voltage level may bedetermined before the frame 410 is processed for reception ortransmission. For example, for a bandwidth BW0 a corresponding voltagelevel (V0) is identified. For a higher bandwidth BW1, a differentvoltage level (V1) that is higher than that for BW0 is identified.Similarly for BW2 through BWn and corresponding voltage levels V2through Vn. Once determined, the voltage level is applied to process theentire frame 410.

Turning next to FIG. 4D, a diagram 400-c is shown that includes theframe or packet 410 of FIGS. 4A-4C. FIG. 4D describes a mechanism bywhich it is determined whether the frame 410 is directed or destined forthe wireless communications device (e.g., UE 115, AP 120, eNB 105,device 300) that received it. As described above, when the voltage level440 is appropriate for processing, no change is made and the voltagelevel is maintained at V0. However, when the voltage level (andcorresponding digital clock frequency) needs to be scaled, the voltagelevel is changed during the period 455 to the voltage level 445 (V1). Inthis example, there is a region 431 in the portion 430 (e.g., dataportion), which includes information about the destination of the frame410. The region 431 may correspond to, for example, the MAC RA. When theframe 410 is not destined for the wireless communications device, thereis no reason to proceed processing it and the voltage level may returnto the first voltage level 440 during a period 463 and remain at thelower voltage level for a period 464 until a next frame or packet is tobe handled. However, when the frame 410 is destined for the wirelesscommunications device, the second voltage level 445 is maintainedthrough periods 463 and 464. FIG. 4E shows a diagram 400-d thatillustrates the case when the region 431 is in the portion 420 (e.g.,preamble, header). In this example, the information about thedestination of the frame 410 may be included in a field (e.g., VHT-SIG-Afor VHT packets) in the portion 420 instead of in the MAC RA as in FIG.4D.

Turning next to FIG. 5A, a diagram 500 is shown that includes a frame orpacket 510. The frame 510 may comprise one or more packets and may be anexample of the frame 410 of FIGS. 4A-4E. The frame 510 may include alegacy short training field (L-STF) 511, a legacy long training field(L-LTF) 512, a legacy signal (L-SIG) field 513, a very high throughput(VHT) signal A (VHT-SIG-A) field 514, a VHT short training field(VHT-STF) 515, a VHT long training field (VHT-LTF) 516, a VHT signal B(VHT-SIG-B) field 517, and a data field 518. FIG. 5A, like FIG. 4Aabove, describes a mechanism by which a wireless modem (e.g., UE 115, AP120, eNB 105, device 300) may first operate at a first voltage level 540(V0), may then detect within the frame 510 a frame metric associatedwith one or more packets of the frame 510, and may then determinewhether to transition to a second voltage level 545 (V1) to process atleast a portion of the one or more packets of the frame 510 based on thedetected frame metric. As noted above with respect to FIG. 4A, the firstvoltage level 540 may correspond to one digital clock frequency and thesecond voltage level 545 may correspond to a higher digital clockfrequency.

In this example, the detection of a throughput category may occur withina period 550 (approximately 29 μs) and may include obtaining throughputcategory information from one or more of the fields in this period. Forexample, throughput category information (e.g., whether a packet orframe is HT or VHT, the bandwidth of the packet or frame) may beobtained from the VHT-SIG-A field 514. Once the throughput category isobtained, the determination of whether the frame 510 has a throughputthat involves a higher voltage level is made. When the current voltagelevel (V0) (and corresponding digital clock frequency) is sufficient toprocess the frame 510 (i.e., throughput category does not involve ahigher voltage level), no change is made and the current voltage levelis maintained. When the current voltage level is not sufficient and thesecond voltage level (V1) is needed to properly process the data field518, a voltage transition (i.e., scaling) occurs during a period 555(approximately 3 μs) until the appropriate voltage level (V1) isreached. The period 555 may coincide with the VHT-STF 515 of frame 510.A period 560 (which may be in the millisecond range) corresponds to theapplication of the higher voltage level for digital processing of theVHT-LTF 516, the VHT-SIG-B field 517, and the data field 518.

In some embodiments, the amount of power reduction that may be achievedduring the period 550 by using dynamic voltage and frequency scaling maybe further enhanced if such techniques are also applied to the radiofrequency components of the wireless modem (e.g., transceiver module350).

FIG. 6 shows a diagram 600 that illustrates an example of inframedetection for various IEEE 802.11 packets according to variousembodiments. The diagram 600 includes a packet or frame 610 thatcorresponds to an IEEE 802.11a/g packet, a packet or frame 630 thatcorresponds to an IEEE 802.11n packet, and a packet or frame 650 thatcorresponds to an IEEE 802.11 ac packet.

The frame 610 includes an L-STF field 611, an L-LTF 1&2 field 612, anL-SIG field 613, and a data field 614. When inframe inspection fordetecting the frame metric of the frame 610 identifies the frame 610 asa legacy frame, a voltage level 620 (V0) (and corresponding digitalclock frequency) applied at the beginning of the frame 610 may bemaintained for processing the entire frame.

The frame 630 includes an L-STF field 631, an L-LTF 1&2 field 632, anL-SIG field 633, an HT-SIG 1&2 field 634, and HT-STF field 635, HT-LTFsfield 636, and a data field 637. When inframe (e.g., within frame)inspection for detecting the frame metric of the frame 630 identifiesthe frame 630 as a high throughput (HT) frame, a voltage level 640 (V0)is applied at the beginning of the frame 630 and it is subsequentlyscaled to a higher voltage level 645 (V1) during the HT-STF 635. Thehigher voltage level 645 may be maintained to process the HT-LTFs field636 and the data field 637. The voltage scaling in this case alsoresults in a corresponding digital clock frequency scaling.

The frame 650 includes an L-STF field 651, an L-LTF 1&2 field 652, anL-SIG field 653, a VHT-SIG-A field 654, a VHT-STF field 655, a VHT-LTFsfields 656, and a VHT-SIG-B and data field 657. The frame 650 may be anexample of the frame 510 described above with reference to FIG. 5. Wheninframe inspection for detecting the frame metric of the frame 650identifies the frame 650 as a very high throughput (VHT) frame, avoltage level 660 (V0) is applied at the beginning of the frame 650 andit is subsequently scaled to a higher voltage level 665 (V2) during theVHT-STF field 655. The voltage level 665 (V2) may be higher than thevoltage level 645 (V1) of the frame 630. In some examples, V0 may beabout 0.9V, V1 may be about 1.1V, and V2 may be higher than 1.1V. Thehigher voltage level 665 may be maintained to process the VHT-LTFs field656 and the VHT-SIG-B and data field 657. The voltage scaling in thiscase also results in a corresponding digital clock frequency scaling.

Another consideration that may be taken with respect to the examplesshown in FIG. 6 is whether the frames or packets are destined ordirected to the UE device that is handling them. FIG. 4D and FIG. 4Eprovide a general description of what may occur to voltage (and/orfrequency) scaling when a frame or packet is directed to the device andwhat may occur to the voltage (and/or frequency) scaling when the frameor packet is not directed to the device. For example, when the packet isa high-bandwidth packet (e.g., VHT) and is not directed to the devicehandling it, the voltage level may transition back to a low voltagelevel after pAID in the VHT-SIG-A. When the packet is a 40 MHz packet(e.g., HT or IEEE 11n) and is not directed at the device handling it,the voltage level may transition back to a lower voltage after the MACRA field. Whether clock gating, power gating, and/or voltage scaling isused in any one of these scenarios may depend on what remains of thepacket after the point when it was determined that the packet is notdirected to the device.

There may be additional considerations to be made regarding transitionsassociated with dynamic voltage and frequency scaling. For example, theinitial portion of a listen stage or mode may be started at a reducedVdd. In some cases, the transition to a higher Vdd may be done early onright after automatic gain control (AGC) detects a valid WLAN signal(see e.g., FIG. 7). In these cases, when dynamic voltage and frequencyscaling (DVFS) is implemented right after AGC (i.e., step up to nominalVdd), it may lead to DVFS thrashing if a PHY layer error is found duringthe listen stage and the PHY (e.g., PHY module 330) goes back to searchmode and switches back to reduced Vdd. The fast change in Vdd may leadto a in-rush power wasted due to LDO/SPMS transitions. In other words,the power used between increasing the voltage level early on and thereducing it once an error is found may result in more power beingconsumed than saved. On the other hand, because the increase to a higherVdd occurs early on, the slew rate (i.e., scaling transition) or the PMUmodule 360 may be relaxed as the transition may take place over a longerperiod of time.

In other cases, the transition to a higher Vdd may take place after theVHT-SIG-A field (e.g., VHT-SIG-A field 654) identifies that a higherclock may be required. In these cases, when DVFS is implemented later inthe frame or packet, more power may be saved during the listen stage.However, a later DVFS may involve more challenging slew rates (e.g.,shorter scaling transitions) on a PMIC (e.g., 0.2V/4 us or even higher).

As described above, a PHY layer error may result in DVFS thrashing whenAGC detection for DVFS is implemented early in a frame or packet. PHYlayer errors may occur for multiple reasons and at different places in aframe or packet.

FIG. 7 shows a diagram 700 that illustrates different events, some ofwhich are triggers for PHY layer errors. The diagram 700 includes aframe 710 having an L-STF field 711, an L-LTF 1 field 712, an L-LTF 2field 713, an L-SIG field 714, an HT-SIG 1/2 field 715, an HT-STF field716, an HT-LTFs field 717, and an HT data field 718. Each of the eventsshown in FIG. 7 is connected to a field in the frame 710 where thatevent occurs. Moreover, the diagram 700 also illustrates where AGCdetection occurs (L-STF field 711) when DVFS is implemented early in theframe 710.

The dashed circles shown above the frame 710 identify events associatedwith various aspects of the fields of the frame 710. For example, events1, 2, 3, and 4 are associated with the L-STF field 711, while events 15and 16 are associated with the HT data field 718. The various eventsabove the frame 710 are as follows: 1—drop gain; 2—find strong in-bandsignal; 3—voting for OFDM; 4—coarse DC/ppm; 5—step (coarse timing);6—fine DC; 7—fine timing; 8—fine ppm; 9—channel estimation (chan. est.);10—rate length; 11—find ht packet (pkt); 12—ht fine ppm; 13—modulationand coding scheme (mcs) length 20/40 aggressive (aggr.) short guardinterval (sgi.) etc.; 14—ht fine timing; 15—ht channel estimation (cha.est.); and 16—start data detection (det) and tracking.

The dashed squares shown below the frame 710 identify events that maytrigger PHY layer errors associated with the frame 710. Each of theseevents corresponds to a particular field of the frame 710. For example,events 1 and 2 are associated with the L-STF field 711, while event 9 isassociated with the HT data field 718. The various events below theframe 710 are as follows: 1—voting for cck; 2—scorr low; 3—xcorr low;4—fine timing error; 5—step time out; 6—long scorr low; 7—illegalrate/length or parity error; 8—ht-sig cyclic redundancy check (crc)error; and 9—power drop/high. When one of the events occurs, an errormay be produced and dynamic voltage and frequency scaling may involvehaving to bring a previously increased voltage level back to a lowervoltage level, which may result in thrashing.

As described above, dynamic voltage and frequency scaling (e.g., inframeDVFS) may be applied in various modes of communication. It may also beapplied over an entire subsystem, or over various subsystems, of awireless modem (e.g., device 300). By using separate and independentvoltage islands associated with different subsystems, a more flexiblepower saving scheme may be implemented. For example, one subsystem mayinclude the following components: AMBA (e.g., CPU module 310,Interconnect fabric etc.)), MAC (e.g., MAC module 320), BB (e.g.,baseband module 340), RF (e.g., transceiver module 350), and MEM (e.g.,MEM 370). The subsystem may also include one or more interfaces. Thefollowing representation may indicate the subsystem having the samesource of voltage and its components: {AMBA, MAC, BB, RF, MEM}. Thisvoltage subsystem involves most of the components of, for example, awireless modem. However, a voltage subsystem may involve fewer anddifferent components. Other examples of subsystems are {MAC, BB}, {MAC,BB, RF}, {AMBA, MAC, BB, MEM}. These voltage subsystems may involve theuse of level shifters and voltage isolation, for example. Each voltagesubsystem may have a corresponding digital clock frequency that may bescaled along with the voltage level of the voltage subsystem.

Dynamic voltage and frequency scaling may not be suitable for memorydevices in some situations. For example, internal memory (e.g., SRAM)may or may not be voltage scaled and functional, depending on Vddminrequirements of memory libraries. The retention of memory, during deepsleep, however, may be accompanied by voltage scaling. In general,inframe DVFS typically may not apply to deep sleep, however, there maybe cases when it does. Also, double data rate (DDR) digital logic blocksmay not, in some cases, be suitable to on-the-fly clock/voltage scalingbecause of the presence of a delay-locked loop (DLL). In those cases,the memory may be included in a non-DVFS domain.

Other architectural considerations may include allowing for a CPU,interfaces (e.g., AXI/AHB/APB) and the associated bridges (e.g., X2H,H2P etc.) to be scaled in both frequency and voltage. Those blocks orcomponents that are not amenable to on-the-fly clock changes may beplaced out of a DVFS domain (e.g., PCIE/USB PHY, SERDES, etc.). FIG. 8Aand FIG. 8B described below show different examples of voltagesubsystems used in connection with dynamic voltage and frequencyscaling.

FIG. 8A shows a diagram 800 that illustrates an example of a device 810where each of the components is included in an independent voltagedomain. According to the architecture of FIG. 8A, a PHY 330-a with aheader switch 825 and a DVFS 1 820, a MAC 320-a with a header switch 825and a DVFS 2 820, and a CPU 310-a with a header switch 825 and a DVFS 3820, are each in a different DVFS (e.g., inframe DVFS) domain. Thesedomains are separated by isolation/level shifters 840. The PHY 330-a,the MAC 320-a, and the CPU 310-a may be examples of the PHY 330, the MAC320, and the CPU 310 of FIG. 3, respectively.

In addition to the DVFS domains supported by the DVFS 1 820, the DVFS 2820, and the DVFS 3 820, an “Always On Domain” module 830 may provideappropriate voltage and/or frequency for the continuous operation of theisolation/level shifters 840. Moreover, the serial interfaces and memory860 with a header switch 825 and a static voltage regulator 850 may bepart of a separate, static, and non-DVFS domain. Note that the threeDVFS domains, the “Always On” domain, and the static domain are allprovided with the same voltage level, Vin, which may originate from acommon source.

The DVFS 1 820, DVFS 2 820, and DVFS 3 820 create unique supply railsper digital block and can each be a switching regulator or an LDO. Thestatic voltage regulator 850 creates a unique supply rail that is afixed voltage and can be a switching regulator or an LDO.

FIG. 8B shows a diagram 800-a that illustrates an example of a device810-a where each of the components is included in an independent domain.According to the architecture of FIG. 8B, a receiver (RX) 870 with aheader switch 825-a and a DVFS 1 820-a, and a transmitter (TX) 875 witha header switch 825-a and a DVFS 2 820-a, are each in a different DVFSdomain. These domains are separated by isolation/level shifters 840-a.The RX 870 and the TX 875 may be examples of an RF receiver and an RFtransmitter, respectively, which may be included in the transceivermodule 350 of FIG. 3.

In addition to the DVFS domains supported by the DVFS 1 820-a and DVFS 2820-a, an “Always On Domain” module 830-a may provide appropriatevoltage and/or frequency for the continuous operation of theisolation/level shifters 840-a. Moreover, the crystal (XTAL)/RFphase-locked loop (PLL)/BIAS 880 with a header switch 825-a and a staticvoltage regulator 850-a may be part of a separate, static, and non-DVFSdomain. Note that the two RF DVFS domains, the “Always On” domain, andthe static domain are all provided with the same voltage level, Vin,which may originate from a common source.

The DVFS 1 820-a and the DVFS 2 820-a create unique supply rails perdigital block and can each be a switching regulator or an LDO. Thestatic voltage regulator 850-a creates a unique supply rail that is afixed voltage and can be a switching regulator or an LDO. In someinstances, there may be multiple static voltage regulators 850-a peranalog block that requires a fixed supply independent of the PHY rate.

The use of dynamic voltage and frequency scaling for RF and/or analogmodules as shown in FIG. 8B may also be implemented in accordance todifferent modes of operation. For example, in a static mode, the voltageto the RF/Analog modules from a low noise amplifier (LNA) to ananalog-to-digital converter (ADC) may be scaled, tying the RF scaling tothe digital dynamic voltage and frequency scaling. In some cases,scaling the voltage may increase the analog receive gain (RxGain).Compensation circuits may be used in the RX path to mitigate anypossible increases of RxGain. The compensation circuits may beimplemented after the RxGain effects have been characterized. Anotherapproach that may mitigate or minimize the effect of scaling inRF/analog modules may be to scale the baseband blocks independently fromthe RF blocks.

In a dynamic mode, RF analog filters may be switched from a lowerbandwidth to a higher bandwidth in a timeline that corresponds to thatof dynamic voltage and frequency scaling (e.g., duration of <10 us).However, implementing fast analog filter switching may present somechallenges. Other aspects may include having RF PLL, BIAS, and XTAL in astatic voltage domain as shown in FIG. 8B. Moreover, the transmit (TX)and receive (RX) blocks of the RF portion of a wireless modem may be onindependent DVFS voltage domains as shown in FIG. 8B.

Turning next to FIG. 9A, a diagram 900 is shown that illustrates adevice 910 in which the voltages for a BB 930, a MAC 940, and asystem-on-chip (SOC) 950 are being scaled directly and independently bydifferent switched-mode power supplies (SMPS) 920. The BB 930 may be anexample of the baseband module 340 of FIG. 3. The MAC 940 may be anexample of the MAC modules 320 and 320-a of FIG. 3 and FIG. 8A,respectively. The SOC 950 may be an example of the CPU modules 310 and310-a of FIG. 3 and FIG. 8A, respectively.

The following expressions describe the power analysis associated withthe dynamic voltage scaling using SMPSs 940 (i.e., direct scaling):V _(SCALED) =V _(SMPS)I _(LOAD) =C×V _(SMPS) ×FI _(BATT) =I _(LOAD)×(V _(SMPS) /V _(BATT))×(1/e)P=V _(BATT) ×I _(BATT)where V_(SCALED)=output of the SMPS, e=efficiency of SMPS,I_(BATT)=current drawn at battery, V_(BATT)=battery voltage,I_(LOAD)=current drawn at each block; C=load capacitance, F=blockoperational frequency, and P=power. The power calculations may be asfollows:Power before scaling: (C×F)×(V _(SMPS))²×(1/e)Power after scaling: (C×F)×(V _(SCALED))²×(1/e)which results in power savings that may be proportional to V² atV_(BATT).

Turning to FIG. 9B, a diagram 900-a is shown that illustrates a device910-a in which the voltages for a BB 930-a, a MAC 940-a, and an SOC950-a are being scaled indirectly and independently by different SMPS920-a through LDOs 960. The BB 930-a may be an example of the basebandmodule 340 of FIG. 3 and the BB 930 of FIG. 9A. The MAC 940-a may be anexample of the MAC modules 320 and 320-a of FIG. 3 and FIG. 8A,respectively, and of the MAC 940 of FIG. 9A. The SOC 950-a may be anexample of the CPU modules 310 and 310-a of FIG. 3 and FIG. 8A,respectively, and of the SOC 950 of FIG. 9A. The SMPS 920-a may be anexample of the SMPS 920 of FIG. 9A.

The following expressions describe the power analysis associated withthe dynamic voltage scaling using SMPSs 940-a and LDOs 960 (i.e.,indirect scaling):V _(SCALED) =V _(LDO)I _(LOAD) =C×V _(LDO) ×F+I _(BIAS)I _(BATT) =I _(LOAD)×(V _(SMPS) /V _(BATT))×(1/e)P=V _(BATT) ×I _(BATT)where some of these terms are common to those described above for theanalysis with respect to FIG. 9A. Moreover, V_(LDO)=output of the LDOand I_(BIAS)=LDO bias current. The power calculations may be as follows:Power before scaling: (C×F)×(V _(SMPS))²×(1/e)Power after scaling: (C×F)×(V _(SCALED))×(V _(SMPS))×(1/e) (notincluding LDO bias current)Power after scaling: (V _(SMPS))×(C×F×V _(SCALED) +I _(BIAS))×(1/e)(including LDO bias current)

In an example that provides comparison between the implementation of thedevice 910 and the device 910-a in FIG. 9A and FIG. 9B, respectively,the following assumptions may be made:V _(BATT)=3.6 VV _(SMPS)=1.05 VV _(SCALED)=0.8 VI _(BIAS)=50 μAe(fficiency)=0.9C×F=10⁻³Nominal block current=C×F×V _(SMPS) =C×F×(1.05 V)Under these conditions, the calculated power without the use of DVFS maybe 12.25 mW. The calculated power when DVFS and direct scaling (i.e.,SMPS as shown in FIG. 9A) are used may be 7.1 mW, approximately a 42%reduction in the amount of power used. The calculated power when DVFSand indirect scaling (i.e., SMPS/LDO as shown in FIG. 9B) are used andthe LDO bias is ignored may be 9.33 mW, approximately a 24% reduction inthe amount of power used. The calculated power when DVFS and indirectscaling (i.e., SMPS/LDO as shown in FIG. 9B) are used and the LDO biasis included may be 9.39 mW, approximately a 23% reduction in the amountof power used. From these results, direct scaling may be used to providea larger reduction in the amount of power used. This approach may beeasy to implement in an integrated solution with an external PMIC withmultiple DVFS capable SMPSs. Indirect scaling, on the other hand, may besuitable in discrete (not integrated) solutions. Note that the voltagescaling outlined in FIG. 9A and FIG. 9B may be used to scalecorresponding clock frequencies used for processing digital data.

The various techniques described herein for implementing dynamic voltageand frequency scaling may also be applicable to wireless modems used incellular communications such as those use in UEs for LTE networks. Beloware provided some embodiments that implement features or aspects ofdynamic voltage and frequency scaling into LTE-based communications.

FIG. 10 shows a diagram 1000 that illustrates an example of framestructure that may be used in a wireless communication system, includingthe wireless communication systems described above with reference toFIG. 1 and FIG. 2. The frame structure may be used in LTE or similarsystems. A frame (10 ms) 1010 may be divided into 10 equally sizedsub-frames. Each sub-frame may include two consecutive time slots. Aresource grid may be used to represent two time slots, each time slotincluding a resource block (RB). The resource grid may be divided intomultiple resource elements.

In LTE, a resource block may contain 12 consecutive subcarriers in thefrequency domain and, for a normal cyclic prefix in each OFDM symbol, 7consecutive OFDM symbols in the time domain, or 84 resource elements.The number of bits carried by each resource element may depend on themodulation scheme. Thus, the more resource blocks that a UE receives andthe higher the modulation scheme, the higher the data rate may be forthe UE.

In this example, the first 1-3 or 1-4 OFDM symbols in the first slot maybe used as a control region that includes control signaling symbols(dotted) and cell-specific reference symbols (CR-RS) (diagonal lines).The CR-RS may also be included in the remaining portion of the firstslot and in the second slot. Control information provided in the controlsignaling symbols may include control information for one or multipleUEs contained in downlink control information (DCI) messages transmittedthrough physical downlink control channel (PDCCH).

Dynamic voltage and frequency scaling may be implemented in connectionwith the decoding stage of PDCCH. For example, each PDCCH or controlregion (i.e., first 3 or 4 OFDM symbols) may needs to be decoded at a 1ms periodicity. A UE (e.g., UE 115), however, may or may not havedownlink (DL) or reception grant or an uplink (UL) or transmission grantgiven to it. Because such grant may not be provided for a portion of thesub-frame, the remaining 11 or 10 OFDM symbols in the sub-frame may beignored (i.e., not processed). When a DCI UL/DL grant is offered to theUE through the PDCCH, the UE may receive information about the resourceblock (RB) associated with the grants. The DL RB may be in the nextslot, in which case the UE time may have between 3 and 4 OFDM symbols inthe first slot to scale the clock and/or the voltage down before itneeds to ready for the assigned DL grant.

When the grant is an UL grant, for example, which may be determined bydecoding the first 1-3 or 1-4 OFDM symbols, the UE may ignore theremainder of the first slot and may clock gate with power scaling (i.e.,reduced Vdd, reduced clock) the second slot of the sub-frame. The ULtypically takes place 4 sub-frames after the grant. For the next PDCCH,which occurs in the next sub-frame 1 ms later, the UE may get the clockback up for decoding the PDCCH control information, which may provide aDL grant (for that sub-frame) or another UL grant 4 ms later.

When the grant is a DL grant in the same sub-frame as the 1-3 or 1-4OFDM symbols from which the grant is determined, the UE may ignore theremaining OFDM symbols in the first slot and may operate during thefirst slot at a reduced Vdd (and corresponding lower clock). For thesecond slot, the UE may increase the Vdd (and the clock) back up tohandle the DL.

Because each OFDM symbol has a duration of approximately 71 μs,implementing dynamic voltage and frequency scaling as described abovefor LTE slots and sub-frames may provide a significant amount of powersavings in the operation of a wireless modem in a UE.

Turning next to FIG. 11A, a diagram 1100 illustrates a chart 1110 thatdescribes long and short discontinuous reception (DRX) intervals duringan active data connection in LTE for use in connection with dynamicvoltage and frequency scaling. DRX intervals allow a UE (e.g., UE 115)to switch off its receiver for a period of time before it needs to turnit back on to receive or listen to signals. The chart 1110 shows both along DRX, which may be configured by a radio resource control (RRC)message, for example. The chart 1110 also shows a short DRX, which mayalso be configured by an RRC message. Packets 1120 are shown toillustrate the pattern of information associated with the long and shortDRXs of chart 1110. The packets 1120 may be realtime packets (e.g.,Voice-over-IP (VoIP) packets) transmitted to the UE.

During the DRX intervals or DRX cycles, the UE may stop or discontinuedecoding the PDCCH. Thus, one approach to implement dynamic voltage andfrequency scaling with DRX intervals may include that, at an entry intoa DRX interval (long or short), the digital modem of the UE device andthe RF subsystem may be frequency scaled and voltage scaled. Dependingon one or more criterion (e.g., the DRX interval length), either clockgating, power gating, and/or voltage scaling may be applied. Forexample, if the duration is long enough, power collapse may be applied.FIG. 11B shows a diagram 1100-a in which a chart 1120 illustrates thetiming of a DRX cycle in connection with PDCCH decoding. In the chart1120, a successful PDCCH decoding starts an inactivity timer (1) whenthe UE is awake. The inactivity timer may expire after certain duration.However, when another successful PDCCH decoding starts before theinactivity timer expires, the inactivity timer may be reset (2). Afterthe inactivity timer expires (3), the DRX cycle may start and dynamicvoltage and frequency scaling may be applied when, for example, the UEis in a sleep or similar mode.

Another aspect of consideration for dynamic voltage and frequencyscaling may be the measurement gaps that occur when an LTE modem (e.g.,device 300) stops or discontinues active DL/UL traffic and begins toscan adjacent cells. During scanning, some operations may be performed.One or more of those operations may include the use of a Fast FourierTransform (FFT). The FFT used during scanning, however, may be smallerthan an FFT used during an active transmit/receive (TX/RX) mode. Forexample, a 64-point FFT may be used during scanning and a 2048-point FFTmay be used during active TX/RX modes. This is because that cellphysical layer identification typically arrives at a reduced bandwidthcentrally located around a center frequency. A scaled clock may be usedfor the smaller FFT during scanning, which may be combined with voltagescaling of the digital modem of the UE device and the RF subsystem toprovide greater power savings.

FIG. 11C shows a diagram 1100-b in which a frame sequence 1130illustrates various aspects of dynamic voltage and frequency scalingduring measurement gaps. As shown in the frame sequence 1130, a gap(e.g., 6 ms) may arise every 40 ms or 80 ms, approximately, during aconnected TX/RX mode. The gap in this example is shown in connectionwith a block A of six sub-frames in frame N. During this gap, the UEdevice (e.g., UE 115) may perform inter-frequency measurements andreport signal parameters. As noted above, this kind of signal estimationmay be performed using a 64-point FFT (where the physical layer channelprimary broadcast channel (P-SCH) and the secondary synchronizationchannel (S-SCH) reside). The P-SCH and S-SCH typically refer to thecentral 72-subcarriers. When scaling (e.g., a scaled mode is applied)involves scaling a clock, the scaling may also involve voltage scaling.Block B shown in FIG. 11C illustrates a block of four sub-frames inwhich DCI0 may not be transmitted because a corresponding to a physicaluplink shared channel (PUSCH) may fall within the measurement gap.Moreover, a block C of four sub-frames illustrates that a physicalhybrid-ARQ indicator channel (PHICH) for PUSCH sub-frames 3, 4, 5, and 6may not be transmitted because they may be within the measurement gap.

In another aspect related to using dynamic voltage and frequency scalingin LTE, one or more of the scaling schemes or techniques describedherein may be applied to various features of OFDM/A or OFDMA. Forexample, when engaged in a TX/RX mode, a UE (e.g., UE 115), may performa wide-band FFT using a 2048-point FFT. However, OFDM/A typicallyincorporates sub-20 MHz bandwidth blocks across the frequency access.Moreover, these blocks may change in each sub-frame. Generally, cellularchipsets used for OFDM/A applications tend to operate at the highestclock rate to perform wide-band analysis to report channel qualityindication (CQI) wide-band and sub-bands. CQI reporting, however, maynot be needed at all times and dynamic voltage and frequency scaling maybe applied.

For example, an UE (e.g., UE 115) in LTE may not need to reportwide-band CQI. The UE may then get assigned a resource block (e.g.,physical resource block (PRB) of 0.5 ms and 12 sub-carriers) of about 5MHz, for example, which is smaller than the 20 MHz total systembandwidth. The UE may detect this information in the first three or fourOFDM symbols (see e.g., FIG. 10). In such a case, there may be no needto operate at the highest clock for a DL grant. Instead, it may bepossible to scale the clock to process the small bandwidth of data(e.g., 5 MHz), which is offset from the center frequency, and scale thevoltage for the duration of the PRB. This approach may not be applicableto the first three or four OFDM symbols since those symbols are used toobtain the control data, which is wide-band.

The examples described above may allow for having the UE sleep in thefrequency domain based on the characteristics of OFDM/A. Then, clockand/or voltage scaling may be performed at line-rate and based on thePRB assignment. The above scheme may be abandoned for sub-frames wherethe UE is required to report a wideband CQI report to the eNode-B.Furthermore, in the event of a distributed PRB assignment, the highestclock selected may be commensurate with the highest bandwidth from themultiple bandwidths associated with each distributed PRB.

Next is provided information about LTE across its operational bandwidthin connection with implementing dynamic voltage and frequency scaling.For at least some of the modes (e.g., channel bandwidths), for the 76central subcarriers, a 128-point FFT may be used. However, to optimizethe cell search process, the primary synchronization sequence (PSS) andthe secondary synchronization sequence (SSS) may be transmitted in 64subcarriers (e.g., PBCH) to allow for a 64-point FFT to be used. It maybe possible, then, to operate at a scaled clock of 1.92 MHz or lower asthe dynamic range of the clock is quite high. This approach may providegreat flexibility in scaling the voltage for cell search measurementgaps (see e.g., FIG. 11C). A more general approach may be to perform areduced, N-point FFT, select a minimum sample clock that is needed toperform the FFT (e.g., subcarrier frequency spacing×N) as granted by thePRB bandwidth, and scale the voltage at line-rate processing of LTEDL/UL traffic. This more general approach may correspond to theimplementation of a sleep function in the frequency domain.

Turning next to FIG. 12, a diagram 1200 is shown that illustrates an UE115-b configured for dynamic voltage and frequency scaling. The UE 115-bmay be used with cellular networks (e.g., LTE) and connects through basestations, and/or in WLAN or Wi-Fi communications and connects through anaccess point, for example. The UE 115-b may have various otherconfigurations and may be included or be part of a personal computer(e.g., laptop computer, netbook computer, tablet computer, etc.), acellular telephone, a PDA, a digital video recorder (DVR), an internetappliance, a gaming console, an e-readers, etc. The UE 115-v may have aninternal power supply (not shown), such as a small battery, tofacilitate mobile operation. The UE 115-b may be an example of the userequipments 115 of FIG. 1 and FIG. 2. The UE 115-b may include the device300 of FIG. 3, the devices 810 and 810-a of FIG. 8A and FIG. 8B, and/orthe devices 910 and 910-a of FIG. 9A and FIG. 9B. The UE 115-b may bereferred to as a wireless communications device, a user equipment, or astation in some cases.

The UE 115-b may include antennas 1260, a transceiver module 1250, amemory 1220, a processor module 1210, and an interface module 1245,which each may be in communication, directly or indirectly, with eachother (e.g., via one or more buses). The transceiver module 1250 may beconfigured to communicate bi-directionally, via the antennas 1260 and/orone or more wired or wireless links, with one or more networks, asdescribed above. For example, the transceiver module 1250 may beconfigured to communicate bi-directionally with base stations 105 FIG. 1and/or the access points 120 and 120-a of FIG. 1 and FIG. 2. Thetransceiver module 1250 may be implemented as a transmitter module and aseparate receiver module. The transceiver module 1250 may include amodem configured to modulate the packets and provide the modulatedpackets to the antennas 1260 for transmission, and to demodulate packetsreceived from the antennas 1260. The modem may include at least aportion of the device 300 described with respect to FIG. 3. While the UE115-b may include a single antenna, there may be embodiments in whichthe UE 115-b may include multiple antennas 1260.

The memory 1220 may include random access memory (RAM) and read-onlymemory (ROM). The memory 1220 may store computer-readable,computer-executable software code 1225 containing instructions that areconfigured to, when executed, cause the processor module 1210 to performor control various functions described herein for dynamic voltage andfrequency scaling. Alternatively, the software code 1225 may not bedirectly executable by the processor module 1210 but be configured tocause the computer (e.g., when compiled and executed) to performfunctions described herein.

The processor module 1210 may include an intelligent hardware device,e.g., a central processing unit (CPU) such as those made by Intel®Corporation or AMD®, a microcontroller, an ASIC, etc. The processormodule 1210 may process information received through the transceivermodule 1250 and/or to be sent to the transceiver module 1250 fortransmission through the antennas 1260. The processor module 1210 mayhandle, alone or in connection with the DVFS module 1230, variousaspects of dynamic voltage and frequency scaling.

According to the architecture of FIG. 12, the UE 115-b may furtherinclude a communications management module 1240. The communicationsmanagement module 1240 may manage communications with other userequipments 115, with various base stations (e.g., macro cells, smallcells), and/or with various access points. By way of example, thecommunications management module 1240 may be a component of the UE 115-bin communication with some or all of the other components of the UE115-b via a bus (as shown in FIG. 12). Alternatively, functionality ofthe communications management module 1240 may be implemented as acomponent of the transceiver module 1250, as a computer program product,and/or as one or more controller elements of the processor module 1210.

The components of the UE 115-b may be configured to implement aspectsdiscussed above with respect to devices 300, 810, 810-a, 910, and 910-aand those aspects may not be repeated here for the sake of brevity. Thecomponents of the UE 115-b may be configured to implement aspectsdiscussed above with respect to the diagrams in FIG. 4A, FIG. 4B, FIG.4C, FIG. 4E, FIG. 5, and FIG. 6. Moreover, the components of the UE115-b may be configured to implement aspects discussed below withrespect to methods 1600, 1700, 1800, 1900, 2000, and 2100 of FIG. 16,FIG. 17, FIG. 18. FIG. 19, FIG. 20, and FIG. 21, respectively, and thoseaspects may not be repeated here also for the sake of brevity.

The UE 115-b may also include the DVFS module 1230, which as describedabove, may be configured to handle various aspects of dynamic voltageand frequency scaling. The DVFS module 1230 may include a voltageadjustment module 1232. The voltage adjustment module 1232 may performone or more aspects of operating at a first voltage level in the UE115-b; detecting, within a received frame, a frame metric associatedwith one or more packets of the received frame; and determining whetherto transition to a second voltage level to process at least a portion ofthe one or more packets of the received frame based on the detectedframe metric. The frame metric may include one or more of a throughputcategory, a destination of a packet, a transmission grant, and areception grant. The voltage adjustment module 1232 may perform one ormore aspects of determining a bandwidth to be used at the UE 115-b frommultiple bandwidths supported by the UE 115-b; identifying a voltagelevel to use at the UE 115-b based on the determined bandwidth; andscaling a voltage level to the identified voltage level. The voltageadjustment module 1232 may be configured to perform digital clockfrequency adjustments that correspond to the voltage adjustments. Forexample, the voltage adjustment module 1232 may use an increased voltagelevel to produce a higher digital clock frequency and may use a reducedvoltage level to produce a lower digital clock frequency.

The UE 115-b may also include the interface module 1245, which may beconfigured to include a PCIE)/USB/SDIO bridge for the data pipe betweenthe processor module 1210 and a portion of the UE 115-b performing MAClayer operations. The interface module 1245 may be an example of theinterface module 315 in FIG. 3.

Turning to FIG. 13, a diagram 1300 is shown that illustrates a networkdevice 1305. In some embodiments, the network device 1305 may be anexample of the base stations 105 of FIG. 1 and/or the access points 120and 120-a of FIG. 1 and FIG. 2. The network device 1305 may be used in acellular network (e.g., LTE) or for WLAN or Wi-Fi communications. Thenetwork device 1305 may include antennas 1360, transceiver modules 1350,a memory 1320, and a processor module 1310, which each may be incommunication, directly or indirectly, with each other (e.g., over oneor more buses). The transceiver modules 1350 may be configured tocommunicate bi-directionally, via the antennas 1360, with one or moreuser equipments such as the UE 115-b of FIG. 12. The transceiver modules1350 (and/or other components of the network device 1305) may also beconfigured to communicate bi-directionally with one or more networks. Insome cases, the network device 1305 may communicate with a core network130-a through a network communications module 1370. The core network130-a may be an example of the core network 130 of FIG. 1. The networkdevice 1305 may be an example of an eNodeB base station, a Home eNodeBbase station, a NodeB base station, and/or a Home NodeB base station.The network device 1305 may also be an example of an access point.

The network device 1305 may also communicate with other network devices,such as the network device 1305-a and the network device 1305-b. In oneexample, the network device 1305-a may be another access point. Inanother example, the network device 1305-b may be a base station throughwhich the network device 1305 may establish a cellular connection. Eachof the network devices 1305, 12305-a, and 1305-b may communicate with auser equipment using different wireless communications technologies,such as different Radio Access Technologies. In some cases, the networkdevice 1305 may communicate with other network devices using a networkdevice communications module 1380. In some embodiments, the networkdevice communications module 1380 may provide an X2 interface within anLTE wireless communication technology to provide communication betweensome of the network devices. In some embodiments, the network device1305 may communicate with other network devices through the core network130-a.

The memory 1320 may include RAM and ROM. The memory 1320 may also storecomputer-readable, computer-executable software code 1322 containinginstructions that are configured to, when executed, cause the processormodule 1310 to perform various functions described herein for dynamicvoltage and frequency scaling. Alternatively, the software code 1322 maynot be directly executable by the processor module 1310 but beconfigured to cause the computer, e.g., when compiled and executed, toperform functions described herein.

The processor module 1310 may include an intelligent hardware device,e.g., a CPU, a microcontroller, an ASIC, etc. The processor module 1310may process information received through the transceiver modules 1350,the network device communications module 1380, and/or the networkcommunications module 1370. The processor module 1310 may also processinformation to be sent to the transceiver modules 1350 for transmissionthrough the antennas 1360, to the network device communications module1380, and/or to the network communications module 1370. The processormodule 1310 may handle, alone or in connection with the DVFS module1330, various aspects of dynamic voltage and frequency scaling.

The transceiver modules 1350 may include a modem configured to modulatethe packets and provide the modulated packets to the antennas 1360 fortransmission, and to demodulate packets received from the antennas 1360.The modem may include at least a portion of the device 300 describedabove with reference to FIG. 3. The transceiver modules 1350 may beimplemented as a transmitter module and a separate receiver module.

According to the architecture of FIG. 13, the network device 1305 mayfurther include a communications management module 1340. Thecommunications management module 1340 may manage communications withother network devices. By way of example, the communications managementmodule 1340 may be a component of the network device 1305 incommunication with some or all of the other components of the networkdevice 1305 via a bus (as shown in FIG. 13). Alternatively,functionality of the communications management module 1350 may beimplemented as a component of the transceiver modules 1350, as acomputer program product, and/or as one or more controller elements ofthe processor module 1310.

The components for the network device 1305 may be configured toimplement aspects discussed above with respect to devices 300, 810,810-a, 910, and 910-a and those aspects may not be repeated here for thesake of brevity. The components of the network device 1305 may beconfigured to implement aspects discussed above with respect to thediagrams in FIG. 4A, FIG. 4B, FIG. 4C, FIG. 4E, FIG. 5, and FIG. 6.Moreover, the components for the network device 1305 may be configuredto implement aspects discussed below with respect to methods 1600, 1700,1800, 1900, 2000, and 2100 of FIG. 16, FIG. 17, FIG. 18. FIG. 19, FIG.20, and FIG. 21, respectively, and those aspects may not be repeatedhere also for the sake of brevity.

The network device 1305 may also include the DVFS module 1330, which asdescribed above, may be configured to handle various aspects of dynamicvoltage and frequency scaling. The DVFS module 1330 may include avoltage adjustment module 1332. The voltage adjustment module 1332 mayperform one or more aspects of operating at a first voltage level in thenetwork device 1305; detecting, within a received frame, a frame metricassociated with one or more packets of the received frame; anddetermining whether to transition to a second voltage level to processat least a portion of the one or more packets of the received framebased on the detected frame metric. The frame metric may include one ormore of a throughput category, a destination of a packet, a transmissiongrant, and a reception grant. The voltage adjustment module 1332 mayperform one or more aspects of determining a bandwidth to be used at thenetwork device 1305 from multiple bandwidths supported by the networkdevice 1305; identifying a voltage level to use at the network device1305 based on the determined bandwidth; and scaling a voltage level tothe identified voltage level. The voltage adjustment module 1332 may beconfigured to perform digital clock frequency adjustments thatcorrespond to the voltage adjustments. For example, the voltageadjustment module 1332 may use an increased voltage level to produce ahigher digital clock frequency and may use a reduced voltage level toproduce a lower digital clock frequency.

FIG. 14A shows a diagram 1400 that illustrates a DVFS module 1410, whichmay be an example of the DVFS module 1230 of FIG. 12 and the DVFS module1330 of FIG. 13. The DVFS module 1410 may include an intraframeadjustment module 1420 and a bandwidth adjustment module 1430. The DVFSmodule, or at least portions of it, may be a processor.

The intraframe adjustment module 1420 may be configured to operate at afirst voltage level in a wireless communications device, to detect,within a received frame, a frame metric associated with one or morepackets of the received frame, and to determine whether to transition toa second voltage level to process at least a portion of the one or morepackets of the received frame based on the detected frame metric. Theframe metric may include one or more of a throughput category, adestination of a packet, a transmission grant, and a reception grant.

The intraframe adjustment module 1420 may be configured to scale fromthe first voltage level to the second voltage level, where the secondvoltage level is greater than the first voltage level. The intraframeadjustment module 1420 may be configured to scale from the secondvoltage level to the first voltage level for a next received frame afterprocessing the at least a portion of the one or more packets of thereceived frame at the second voltage level. The detection performed bythe intraframe adjustment module 1420 may include the detection of theframe metric within a preamble of the received frame. In someembodiments, the one or more packets in the received frame is a IEEE802.11ac packet. Moreover, the one or more packets may be a VHT packet,and the detection performed by the intraframe adjustment module 1420includes the detection of the frame metric during the VHT-STF of thereceived VHT packet. The intraframe adjustment module 1420 may beconfigured to scale from the first voltage level to the second voltagelevel within the VHT packet, where the second voltage level is greaterthan the first voltage level.

The intraframe adjustment module 1420 may be configured to determinewhether the frame is destined for the wireless communications device,and to operate at the first voltage level when the frame is not destinedfor the wireless communications device. In some embodiments, thedetermination includes identifying a MAC portion of the frame anddetermining a destination of the frame from the MAC portion of theframe. In other embodiments, the determination includes identifying apAID field or a GID field in the frame, and determining a destination ofthe frame from the pAID field or the GID field.

The intraframe adjustment module 1420 may be configured to handle HTpackets and scale from the first voltage level to the second voltagelevel to process at least a portion of the HT packet, where the secondvoltage level is greater than the first voltage level. The intraframeadjustment module 1420 may be configured to handle a legacy packet andto maintain the first voltage level for processing the legacy packet.

The intraframe adjustment module 1420 may be configured to identify abandwidth associated with the one or more packets of received frame, andto scale from the first voltage level to the second voltage level basedat least in part on the frame metric and the identified bandwidth. Theintraframe adjustment module 1420 may be configured to identify adifferent bandwidth associated with the one or more packets of receivedframe, and to scale from the second voltage level to a third voltagelevel based at least in part on the frame metric and the identifieddifferent bandwidth. The intraframe adjustment module 1420 may beconfigured to scale from a first clock frequency to a second clockfrequency based on the frame metric, where the second clock frequency isgreater than the first clock frequency. Voltage scaling by theintraframe adjustment module 1420 may result in a corresponding digitalclock frequency scaling.

In some embodiments, the frame is an LTE sub-frame having a first slotand a second slot, where the first slot includes a region with PDCCHinformation, and the intraframe adjustment module 1420 may be configuredto detect the frame metric from within the region in the first slot. Theframe metric may be a bandwidth associated with one or more packets ofthe received frame. The intraframe adjustment module 1420 may determinefrom the frame metric whether a portion of the frame is to be decoded byan LTE modem, and may scale from the first voltage to the second voltageto process the portion of the frame when a determination is made thatthe portion of the frame is not to be decoded by the LTE modem. Theintraframe adjustment module 1420 may be configured to apply the secondvoltage level to one or more subsystems of the wireless communicationsdevice.

The bandwidth adjustment module 1430 may be configured to determine abandwidth to be used at a wireless communications device from multiplebandwidths supported by the wireless communications device, to identifya voltage level to use at the wireless communications device based onthe determined bandwidth, and to scale a voltage level to the identifiedvoltage level to process a frame. Voltage scaling by the bandwidthadjustment module 1430 may result in a corresponding digital clockfrequency scaling. In some embodiments, the bandwidth adjustment module1430 is configured to transmit the frame while operating at the scaledvoltage level. In other embodiments, the bandwidth adjustment module1430 is configured to receive the frame having one or more packets, andto process at least a portion of the one or more packets of the receivedframe at the scaled voltage level. The bandwidth adjustment module 1430may be configured to receive the frame having one or more packets,detect, within the received frame, a frame metric associated with one ormore packets of the received frame, and process at least a portion ofthe one or more packets of the received frame at the scaled voltagelevel based on the frame metric and the determined bandwidth. Each ofthe bandwidths supported by the wireless communications device may havea corresponding voltage level that is different from the voltage levelof another bandwidth, and the identified voltage level may be thevoltage level corresponding to the determined bandwidth.

The bandwidth adjustment module 1430 may be configured to adjust, basedon the determined bandwidth, one or more PHY clocks used by the wirelesscommunications device. In some embodiments, the determination performedby the bandwidth adjustment module 1430 may include determining thebandwidth to be used at the wireless communications device based onchannel conditions associated with the wireless communications device.In some embodiments, the scaling performed by the bandwidth adjustmentmodule 1430 may include scaling to the identified voltage level from avoltage level corresponding to a bandwidth different from the determinedbandwidth. The bandwidth adjustment module 1430 may be configured toapply the scaled voltage level to one or more subsystems of the wirelesscommunications device.

The components of the DVFS module 1400 may, individually orcollectively, be implemented with one or more ASICs adapted to performsome or all of the applicable functions in hardware. Each of the notedmodules may be a means for performing one or more functions related tooperation of the DVFS module 1400.

Turning next to FIG. 14B, a diagram 1400-a that illustrates a DVFSmodule 1410-a, which may be an example of the DVFS module 1230 of FIG.12, the DVFS module 1330 of FIG. 13, and the DVFS module 1410 of FIG.14A. The DVFS module 1410-a may include an intraframe adjustment module1420-a and a bandwidth adjustment module 1430-a. The intraframeadjustment module 1420-a may be an example of the intraframe adjustmentmodule 1420 of FIG. 14A. Similarly, the bandwidth adjustment module1430-a may be an example of the bandwidth adjustment module 1430 of FIG.14A. The DVFS module 1410-a, or at least portions of it, may be aprocessor.

The intraframe adjustment module 1420-a may include a voltage adjustmentmodule 1421, a frequency/clock adjustment module 1422, a packettype/property detection module 1423, a packet destination module 1424,and a bandwidth identification module 1425. The voltage adjustmentmodule 1421 may be configured to perform various aspects describedherein related to identifying, selecting, scaling, modifying, oradjusting voltage levels. The frequency/clock adjustment module 1422 maybe configured to perform various aspects described herein related toidentifying, selecting, scaling, modifying, or adjusting frequenciesand/or clocks. The adjustment of frequencies and/or clocks maycorrespond to the adjustment of voltages by the voltage adjustmentmodule 1421. The packet type/property detection module 1423 may beconfigured to perform various aspects described herein related todetermining and identifying packet types and properties, including butnot limited to frame metrics, throughput categories, bandwidths, andgrants. The packet destination module 1424 may be configured to performvarious aspects described herein related to inspecting, identifying, anddetermining destination information for a packet or frame. The bandwidthidentification module 1425 may be configured to perform various aspectsdescribed herein related to identifying one or more bandwidths and/orcorresponding information such as voltage levels.

The bandwidth adjustment module 1430-a may include a voltage adjustmentmodule 1431, a frequency/clock adjustment module 1432, a packettype/property detection module 1433, a channel conditions detectionmodule 1434, and a bandwidth identification module 1435. The voltageadjustment module 1431 may be configured to perform various aspectsdescribed herein related to identifying, selecting, scaling, modifying,or adjusting voltage levels. The frequency/clock adjustment module 1432may be configured to perform various aspects described herein related toidentifying, selecting, scaling, modifying, or adjusting frequenciesand/or clocks. The adjustment of frequencies and/or clocks maycorrespond to the adjustment of voltages by the voltage adjustmentmodule 1431. The packet type/property detection module 1433 may beconfigured to perform various aspects described herein related todetermining and identifying packet types and properties, including butnot limited to frame metrics, throughput categories, bandwidths, andgrants. The channel conditions module 1434 may be configured to performvarious aspects described herein related determine channel conditionsfor selection of a communication bandwidth. The bandwidth identificationmodule 1435 may be configured to perform various aspects describedherein related to identifying one or more bandwidths and/orcorresponding information such as voltage levels.

The components of the DVFS module 1400-a may, individually orcollectively, be implemented with one or more ASICs adapted to performsome or all of the applicable functions in hardware. Each of the notedmodules may be a means for performing one or more functions related tooperation of the DVFS module 1400-a.

Turning to FIG. 15, a block diagram of a multiple-input multiple-output(MIMO) communication system 1500 is shown including a network device1505 and a UE 115-c. The network device 1505 may be an example of thebase stations 105 of FIG. 1, the access points 120 and 120-a of FIG. 1and FIG. 2, and the network device 1305 of FIG. 13. The UE 115-c may bean example of the user equipments 115 and 115-a of FIG. 1 and FIG. 2 andthe UE 115-b of FIG. 12. The system 1500 may illustrate aspects of thenetworks of FIG. 1 and FIG. 2. The network device 1505 may be equippedwith antennas 1534-a through 1534-x, and the UE 115-c may be equippedwith antennas 1552-a through 1552-n. In the system 1500, the networkdevice 1505 may be able to send data over multiple communication linksat the same time. Each communication link may be called a “layer” andthe “rank” of the communication link may indicate the number of layersused for communication. For example, in a 2×2 MIMO system where networkdevice 1505 transmits two “layers,” the rank of the communication linkbetween the network device 1505 and the UE 115-c is two.

At the network device 1505, a transmit (Tx) processor 1520 may receivedata from a data source. The transmit processor 1520 may process thedata. The transmit processor 1520 may also generate reference symbols,and a cell-specific reference signal. A transmit (Tx) MIMO processor1530 may perform spatial processing (e.g., precoding) on data symbols,control symbols, and/or reference symbols, if applicable, and mayprovide output symbol streams to the transmit modulators 1532-a through1532-x. Each modulator 1532 may process a respective output symbolstream (e.g., for OFDM, etc.) to obtain an output sample stream. Eachmodulator 1532 may further process (e.g., convert to analog, amplify,filter, and upconvert) the output sample stream to obtain a downlink(DL) signal. In one example, DL signals from modulators 1532-a through1532-x may be transmitted via the antennas 1534-a through 1534-x,respectively.

At the UE 115-c, the antennas 1552-a through 1552-n may receive the DLsignals from the network device 1505 and may provide the receivedsignals to the demodulators 1554-a through 1554-n, respectively. Eachdemodulator 1554 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 1554 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 1556 may obtainreceived symbols from all the demodulators 1554-a through 1554-n,perform MIMO detection on the received symbols if applicable, andprovide detected symbols. A receive (Rx) processor 1558 may process(e.g., demodulate, deinterleave, and decode) the detected symbols,providing decoded data for the UE 115-c to a data output, and providedecoded control information to a processor 1580, or memory 1582. Theprocessor 1580 may include a module 1581 that may perform functionsrelated to dynamic voltage and frequency scaling (e.g., intraframeDVFS).

On the uplink (UL), at the UE 115-c, a transmit (Tx) processor 1564 mayreceive and process data from a data source. The transmit processor 1564may also generate reference symbols for a reference signal. The symbolsfrom the transmit processor 1564 may be precoded by a transmit (Tx) MIMOprocessor 1566 if applicable, further processed by the demodulators1554-a through 1554-n (e.g., for SC-FDMA, etc.), and be transmitted tothe network device 1505 in accordance with the transmission parametersreceived from the network device 1505. At the network device 1505, theUL signals from the UE 115-c may be received by the antennas 1534,processed by the demodulators 1532, detected by a MIMO detector 1536 ifapplicable, and further processed by a receive processor. The receive(Rx) processor 1538 may provide decoded data to a data output and to theprocessor 1540. The processor 1540 may include a module 1541 that mayperform functions related to dynamic voltage and frequency scaling(e.g., intraframe DVFS). The components of the network device 1505 may,individually or collectively, be implemented with one or more ASICsadapted to perform some or all of the applicable functions in hardware.Each of the noted modules may be a means for performing one or morefunctions related to operation of the system 1500. Similarly, thecomponents of the UE 115-c may, individually or collectively, beimplemented with one or more ASICs adapted to perform some or all of theapplicable functions in hardware. Each of the noted components may be ameans for performing one or more functions related to operation of thesystem 1500.

The communication networks that may accommodate some of the variousdisclosed embodiments may be packet-based networks that operateaccording to a layered protocol stack. For example, communications atthe bearer or Packet Data Convergence Protocol (PDCP) layer may beIP-based. A Radio Link Control (RLC) layer may perform packetsegmentation and reassembly to communicate over logical channels. TheMAC layer may perform priority handling and multiplexing of logicalchannels into transport channels. The MAC layer may also use Hybrid ARQ(HARM) to provide retransmission at the MAC layer to improve linkefficiency. At the PHY layer, the transport channels may be mapped toPhysical channels.

Turning next to FIG. 16, a flowchart is shown of an example method 1600for intraframe dynamic voltage and frequency scaling. The method 1600may be performed using, for example, the user equipments 115 of FIG. 1,FIG. 2, FIG. 2, and FIG. 15; the access points 120 of FIG. 1 and FIG. 2,the network devices 1305 and 1505 of FIG. 13 and FIG. 15; the devices300, 810, 810-a, 910, and 910-a of FIG. 3, FIG. 8A, FIG. 8B, FIG. 9A,and FIG. 9B; and/or the DVFS modules 1230, 1330, 1410, and 1410-a ofFIG. 12, FIG. 13, FIG. 14A, and FIG. 14B.

At block 1605, a wireless communications device (e.g., UE 115, APs 120,base stations 105) may operate at a first voltage level. At block 1610,a frame metric (e.g., throughput category, bandwidth, grant,destination) associated with one of more packets of a received frame maybe detected within the frame. At block 1615, a determination is made asto whether to transition to a second voltage to process at least aportion of the one or more packets of the received frame based on thedetected transmission category.

In some embodiments of the method 1600, the first voltage level isscaled to the second voltage level, where the second voltage level isgreater than the first voltage level. The method may include scalingfrom the second voltage level to the first voltage level for a nextreceived frame after processing the at least a portion of the one ormore packets of the received frame at the second voltage level. Themethod may include detecting the frame metric within a preamble of thereceived frame. In some embodiments, the one or more packets in thereceived frame are IEEE 802.11 ac packets. Moreover, the one or morepackets may be VHT packets, and the detecting may include detecting theframe metric during the VHT-STF of the received VHT packet. The methodmay include scaling from the first voltage level to the second voltagelevel within the VHT packet, where the second voltage level is greaterthan the first voltage level.

In some embodiments of the method 1600, the method may includedetermining whether the frame is destined for the wirelesscommunications device, and operating at the first voltage level when theframe is not destined for the wireless communications device. In someembodiments, the determination includes identifying a MAC portion of theframe and determining a destination of the frame from the MAC portion ofthe frame (e.g., MAC RA). In other embodiments, the determinationincludes identifying a pAID field or a GID field in the frame, anddetermining a destination of the frame from the pAID field or the GIDfield.

In some embodiments of the method 1600, HT packets may be handled andthe scaling includes scaling from the first voltage level to the secondvoltage level to process at least a portion of the HT packet, where thesecond voltage level is greater than the first voltage level. In somecases, legacy packets may be handled and the method includes maintainingthe first voltage level for processing the legacy packet.

In some embodiments of the method 1600, the method includes identifyinga bandwidth associated with the one or more packets of received frame,and scaling from the first voltage level to the second voltage levelbased at least in part on the frame metric and the identified bandwidth.The method may include identifying a different bandwidth associated withthe one or more packets of received frame, and scaling from the secondvoltage level to a third voltage level based at least in part on theframe metric and the identified different bandwidth. The method mayinclude scaling from a first clock frequency to a second clock frequencybased on the frame metric, where the second clock frequency is greaterthan the first clock frequency.

In some embodiments of the method 1600, the frame is an LTE sub-framehaving a first slot and a second slot, where the first slot includes aregion with PDCCH information, and the method includes detecting theframe metric from within the region in the first slot. The frame metricmay be a bandwidth associated with one or more packets of the receivedframe. The method may include applying the second voltage level to oneor more subsystems of the wireless communications device.

Turning next to FIG. 17, a flowchart is shown of an example method 1700for intraframe dynamic voltage and frequency scaling. The method 1700,like the method 1600 above, may be performed using, for example, theuser equipments 115 of FIG. 1, FIG. 2, FIG. 2, and FIG. 15; the accesspoints 120 of FIG. 1 and FIG. 2, the network devices 1305 and 1505 ofFIG. 13 and FIG. 15; the devices 300, 810, 810-a, 910, and 910-a of FIG.3, FIG. 8A, FIG. 8B, FIG. 9A, and FIG. 9B; and/or the DVFS modules 1230,1330, 1410, and 1410-a of FIG. 12, FIG. 13, FIG. 14A, and FIG. 14B.

At block 1705, a wireless communications device (e.g., UE 115, APs 120,base stations 105) may operate at a first voltage level. At block 1710,a frame metric (e.g., throughput category, bandwidth, grant,destination) associated with one of more packets of a received frame maybe detected within the frame. At block 1715, the first voltage level isscaled to a second voltage level, where the value of the second voltagelevel is based on the detected frame metric. At block 1720, the wirelesscommunications device may operate at the second voltage level until atleast a portion of the one or more packets of the received frame areprocessed.

Turning to FIG. 18, a flowchart is shown of an example method 1800 forintraframe dynamic voltage and frequency scaling. The method 1800, likethe methods 1600 and 1700 above, may be performed using, for example,the user equipments 115 of FIG. 1, FIG. 2, FIG. 2, and FIG. 15; theaccess points 120 of FIG. 1 and FIG. 2, the network devices 1305 and1505 of FIG. 13 and FIG. 15; the devices 300, 810, 810-a, 910, and 910-aof FIG. 3, FIG. 8A, FIG. 8B, FIG. 9A, and FIG. 9B; and/or the DVFSmodules 1230, 1330, 1410, and 1410-a of FIG. 12, FIG. 13, FIG. 14A, andFIG. 14B.

At block 1805, a wireless communications device (e.g., UE 115, APs 120,base stations 105) may operate at a first voltage level. At block 1810,a frame metric (e.g., throughput category, bandwidth, grant,destination) associated with one of more packets of a received frame maybe detected within the frame. At block 1815, the first voltage level isscaled to a second voltage level, where the value of the second voltagelevel is based on the detected frame metric. At block 1820, the wirelesscommunications device may operate at the second voltage level to processat least a portion of the one or more packets of the received frame. Atblock 1825, it may be determined whether the one or more packets of thereceived frame are destined or directed to the wireless communicationsdevice. At 1830, the second voltage level may be scaled back to thefirst voltage level when the one or more packet are destined for adifferent device.

Turning next to FIG. 19, a flowchart is shown of an example method 1900for dynamic voltage and frequency scaling. The method 1900, like themethods 1600, 1700, and 1800 above, may be performed using, for example,the user equipments 115 of FIG. 1, FIG. 2, FIG. 2, and FIG. 15; theaccess points 120 of FIG. 1 and FIG. 2, the network devices 1305 and1505 of FIG. 13 and FIG. 15; the devices 300, 810, 810-a, 910, and 910-aof FIG. 3, FIG. 8A, FIG. 8B, FIG. 9A, and FIG. 9B; and/or the DVFSmodules 1230, 1330, 1410, and 1410-a of FIG. 12, FIG. 13, FIG. 14A, andFIG. 14B.

At block 1905, a bandwidth to be used by a wireless communicationsdevice (e.g., UE 115, APs 120, base stations 105) may be determined frommultiple bandwidths supported by the wireless communications device. Atblock 1910, a voltage level is identified to use at the wirelesscommunications device based on the determined bandwidth. At block 1915,a voltage level is scaled to the identified voltage level to process aframe.

In some embodiments of the method 1900, the method includes transmittingthe frame while operating at the scaled voltage level. The method mayinclude receiving the frame having one or more packets, and processingat least a portion of the one or more packets of the received frame atthe scaled voltage level. The method may include receiving the framehaving one or more packets, detecting, within the received frame, aframe metric associated with one or more packets of the received frame,and processing at least a portion of the one or more packets of thereceived frame at the scaled voltage level based on the frame metric andthe determined bandwidth. Each of the bandwidths supported by thewireless communications device may have a corresponding voltage levelthat is different from the voltage level of another bandwidth, and theidentified voltage level may be the voltage level corresponding to thedetermined bandwidth.

In some embodiments of the method 1900, the method includes adjusting,based on the determined bandwidth, one or more PHY clocks used by thewireless communications device. The determining may include determiningthe bandwidth to be used at the wireless communications device based onchannel conditions associated with the wireless communications device.In some embodiments, the scaling may include scaling to the identifiedvoltage level from a voltage level corresponding to a bandwidthdifferent from the determined bandwidth. The method may include applyingthe scaled voltage level to one or more subsystems of the wirelesscommunications device.

Turning to FIG. 20, a flowchart is shown of an example method 2000 fordynamic voltage and frequency scaling. The method 2000, like the methods1600, 1700, 1800, and 1900 above, may be performed using, for example,the user equipments 115 of FIG. 1, FIG. 2, FIG. 2, and FIG. 15; theaccess points 120 of FIG. 1 and FIG. 2, the network devices 1305 and1505 of FIG. 13 and FIG. 15; the devices 300, 800, 810-a, 910, and 910-aof FIG. 3, FIG. 8A, FIG. 8B, FIG. 9A, and FIG. 9B; and/or the DVFSmodules 1230, 1330, 1410, and 1410-a of FIG. 12, FIG. 13, FIG. 14A, andFIG. 14B.

At block 2005, a frame including one or more packets may be received. Atblock 2010, a bandwidth to be used by a wireless communications device(e.g., UE 115, APs 120, base stations 105) may be determined frommultiple bandwidths supported by the wireless communications device. Atblock 2015, a voltage level is identified to use at the wirelesscommunications device based on the determined bandwidth. At block 2020,a voltage level is scaled to the identified voltage level. At block2025, at least a portion of the one or more packets of the receivedframe are processed at the scaled voltage level.

Turning next to FIG. 21, a flowchart is shown of an example method 2100for dynamic voltage and frequency scaling. The method 2100, like themethods 1600, 1700, 1800, 1900, and 2000 above, may be performed using,for example, the user equipments 115 of FIG. 1, FIG. 2, FIG. 2, and FIG.15; the access points 120 of FIG. 1 and FIG. 2, the network devices 1305and 1505 of FIG. 13 and FIG. 15; the devices 300, 810, 810-a, 900, and900-a of FIG. 3, FIG. 8A, FIG. 8B, FIG. 9A, and FIG. 9B; and/or the DVFSmodules 1230, 1330, 1410, and 1410-a of FIG. 12, FIG. 13, FIG. 14A, andFIG. 14B.

At block 2105, channel conditions associated with a wirelesscommunications device (e.g., UE 115, APs 120, base stations 105) may bedetermined. At block 2110, a bandwidth to be used by the wirelesscommunications device may be determined from multiple bandwidthssupported by the wireless communications device. At block 2115, avoltage level is identified to use at the wireless communications devicebased on the determined bandwidth. At block 2120, a voltage level isscaled to the identified voltage level. At block 2125, the frame may betransmitted while operating at the scaled voltage level.

The detailed description set forth above in connection with the appendeddrawings describes exemplary embodiments and does not represent the onlyembodiments that may be implemented or that are within the scope of theclaims. The term “exemplary” used throughout this description means“serving as an example, instance, or illustration,” and not “preferred”or “advantageous over other embodiments.” The detailed descriptionincludes specific details for the purpose of providing an understandingof the described techniques. These techniques, however, may be practicedwithout these specific details. In some instances, well-known structuresand devices are shown in block diagram form in order to avoid obscuringthe concepts of the described embodiments.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,instructions, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope and spirit of the disclosure and appended claims. For example,due to the nature of software, functions described above can beimplemented using software executed by a processor, hardware, firmware,hardwiring, or combinations of any of these. Features implementingfunctions may also be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations. Also, as used herein, including in theclaims, “or” as used in a list of items prefaced by “at least one of”indicates a disjunctive list such that, for example, a list of “at leastone of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., Aand B and C).

Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation,computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media. Any combination of one or more non-transitorycomputer readable medium(s) may be utilized. Non-transitorycomputer-readable media comprise all computer-readable media, with thesole exception being a transitory, propagating signal.

The previous description of the disclosure is provided to enable aperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Throughout this disclosure the term “example” or“exemplary” indicates an example or instance and does not imply orrequire any preference for the noted example. Thus, the disclosure isnot to be limited to the examples and designs described herein; thedisclosure is to be accorded the widest scope consistent with theprinciples and novel features disclosed herein.

What is claimed is:
 1. A method for wireless communications, comprising:operating at a first voltage level in a wireless communications device;detecting, based at least in part on information within a first portionof a received frame, a throughput category corresponding to a bandwidthof one or more packets of the received frame; and determining whether totransition, during processing of the first portion of the receivedframe, to a second voltage level to process at least a portion of theone or more packets including a second portion of the received framebased at least in part on the detected throughput category, wherein thetransition to the second voltage level occurs during processing of thefirst portion of the received frame, and wherein the second portion ofthe received frame is subsequent to the first portion of the receivedframe.
 2. The method of claim 1, further comprising: detecting, based atleast in part on the information within the first portion of thereceived frame or information within the second portion of the receivedframe, one or more of a destination of a packet, a transmission grant,and a reception grant.
 3. The method of claim 1, further comprising:scaling from the first voltage level to the second voltage level, thesecond voltage level being greater than the first voltage level.
 4. Themethod of claim 1, further comprising: scaling from the second voltagelevel to the first voltage level for a next received frame afterprocessing the at least a portion of the one or more packets includingthe second portion of the received frame at the second voltage level. 5.The method of claim 1, wherein the detecting comprises: detecting thethroughput category within a preamble of the received frame.
 6. Themethod of claim 1, wherein: the one or more packets in the receivedframe is an IEEE 802.11 packet.
 7. The method of claim 6, wherein: theone or more packets is a very high throughput (VHT) packet, and thedetecting comprises detecting the throughput category during the VHTshort training field (VHT-STF) of the received VHT packet.
 8. The methodof claim 7, further comprising: scaling from the first voltage level tothe second voltage level within the VHT packet, the second voltage levelbeing greater than the first voltage level.
 9. The method of claim 1,further comprising: determining whether the received frame is destinedfor the wireless communications device; and operating at the firstvoltage level when the received frame is not destined for the wirelesscommunications device.
 10. The method of claim 9, wherein thedetermining comprises: identifying a media access control (MAC) portionof the received frame; and determining a destination of the receivedframe from the MAC portion of the received frame.
 11. The method ofclaim 9, wherein the determining comprises: identifying a pAID field ora GID field in the received frame; and determining a destination of thereceived frame from the pAID field or the GID field.
 12. The method ofclaim 1, wherein the one or more packets is a high throughput (HT)packet, the method comprising: scaling from the first voltage level tothe second voltage level to process at least a portion of the HT packet,the second voltage level being greater than the first voltage level. 13.The method of claim 1, wherein the one or more packets is a legacypacket, the method comprising: maintaining the first voltage level forprocessing the legacy packet.
 14. The method of claim 1, furthercomprising: identifying a bandwidth associated with the one or morepackets of the received frame; and scaling from the first voltage levelto the second voltage level based at least in part on the throughputcategory and the identified bandwidth.
 15. The method of claim 14,further comprising: identifying a different bandwidth associated withthe one or more packets of the received frame; and scaling from thesecond voltage level to a third voltage level based at least in part onthe throughput category and the identified different bandwidth.
 16. Themethod of claim 1, further comprising: scaling from a first clockfrequency to a second clock frequency based at least in part on thethroughput category, the second clock frequency being greater than thefirst clock frequency.
 17. The method of claim 1, wherein: the receivedframe is an LTE sub-frame comprising a first slot and a second slot, thefirst slot comprising a region with physical downlink control channel(PDCCH) information, and the detecting comprises detecting thethroughput category within the region in the first slot.
 18. The methodof claim 17, further comprising: determining from the throughputcategory whether a portion of the received frame is to be decoded by anLTE modem; and scaling from the first voltage level to the secondvoltage level to process the portion of the received frame when adetermination is made that the portion of the received frame is not tobe decoded by the LTE modem.
 19. The method of claim 1, furthercomprising: applying the second voltage level to one or more subsystemsof the wireless communications device.
 20. An apparatus for wirelesscommunications, comprising: means for operating at a first voltage levelin a wireless communications device; means for detecting, based at leastin part on information within a first portion of a received frame, athroughput category corresponding to a bandwidth of one or more packetsof the received frame; and means for determining whether to transition,during processing of the first portion of the received frame, to asecond voltage level to process at least a portion of the one or morepackets including a second portion of the received frame based at leastin part on the detected throughput category, wherein the transition tothe second voltage level occurs during processing of the first portionof the received frame, and wherein the second portion of the receivedframe is subsequent to the first portion of the received frame.
 21. Awireless communications device, comprising: a processor; and a memory inelectronic communication with the processor, instructions stored in thememory being executable by the processor to: operate at a first voltagelevel in the wireless communications device; detect, based at least inpart on information within a first portion of a received frame, athroughput category corresponding to a bandwidth of one or more packetsof the received frame; and determine whether to transition, duringprocessing of the first portion of the received frame, to a secondvoltage level to process at least a portion of the one or more packetsincluding a second portion of the received frame based at least in parton the detected throughput category, wherein the transition to thesecond voltage level occurs during processing of the first portion ofthe received frame, and wherein the second portion of the received frameis subsequent to the first portion of the received frame.
 22. A wirelesscommunications device, comprising: a detector configured to detect,based at least in part on information within a first portion of areceived frame, a throughput category corresponding to a bandwidth ofone or more packets of the received frame; and a voltage adjusterconfigured to: operate at a first voltage level, and determine whetherto transition, during processing of the first portion of the receivedframe, to a second voltage level to process at least a portion of theone or more packets including a second portion of the received framebased at least in part on the detected throughput category, wherein thetransition to the second voltage level occurs during processing of thefirst portion of the received frame, and wherein the second portion ofthe received frame is subsequent to the first portion of the receivedframe.
 23. A computer program product, comprising: a non-transitorycomputer-readable medium comprising: code for causing at least onecomputer to operate at a first voltage level in a wirelesscommunications device; code for causing the at least one computer todetect, based at least in part on information within a first portion ofa received frame, a throughput category corresponding to a bandwidth ofone or more packets of the received frame; and code for causing the atleast one computer to determine whether to transition, during processingof the first portion of the received frame, to a second voltage level toprocess at least a portion of the one or more packets including a secondportion of the received frame based at least in part on the detectedthroughput category, wherein the transition to the second voltage leveloccurs during processing of the first portion of the received frame, andwherein the second portion of the received frame is subsequent to thefirst portion of the received frame.